Sculpt: Pose Brush Face Sets origin mode

This commit introduces a new mode for calculating the positions and
weights of the IK segments in the Pose Brush based on the Face Sets.

The first segment of the chain will always include all face sets inside
the brush radius and it will propagate until the boundary of the last
face sets added in the flood fill. Then consecutive connected face sets
are added to the chain until the chain length limit is reached or all
face sets of the mesh are already part of the chain.

This feature enables complete control over the pose brush origins in
case that is needed. Also, with this mode, the user can have a library
of base meshes with face sets already configured to get to the initial
pose as fast as possible.

Reviewed By: jbakker

Differential Revision: https://developer.blender.org/D7235

Rename Edge Automasking to Mesh Boundary Automasking

This makes more clear what this automasking operation does and helps to differenciate it from the future face sets boundary automasking.

Reviewed By: jbakker

Differential Revision: https://developer.blender.org/D7185

Sculpt: Weight normal and area sampling towards the brush center

Previously, all vertices inside the brush radius were taken into account
equally when calculating the sculpt normal and area. This was causing
artifacts and unpredictable results with large brushes or meshes with
curvatures, as the strongest deformation point of all brushes is usually
in the center. By weighting the vertex normal and position towards the
center when sampling, all brushes should now behave in a more
predictable way in non-uniform surfaces.

Reviewed By: jbakker

Differential Revision: https://developer.blender.org/D6989

Fix T74637: Reset face set data when disabling dyntopo

Last time I checked Face Sets were preserved in a more or less
predictable way when modifying the mesh with dyntopo. As it looks that
in some problems this may cause bugs and you can't see or use face sets
when modifying the topology of the mesh whith dyntopo active, it is
probably better to reset them when going from dyntopo to mesh. This way
you know that you are always going to get a predictable face sets state.

Reviewed By: jbakker

Maniphest Tasks: T74637

Differential Revision: https://developer.blender.org/D7099

Sculpt: Create Face Set by Edit Mode Selection

This implements a new mode in the Face Sets Create operator to create a
new face sets from the faces selection in edit mode. This can be used
when the user considers that the edit mode tools are more convenient for
a more precise control or a certain type of selection, like creating a
face set from a face loop.

Reviewed By: jbakker

Differential Revision: https://developer.blender.org/D7211

Sculpt: Face Sets Init operator

This operator initializes all face sets in the sculpt at once using
different mesh properties. It can create face sets by mesh connectivity,
material slots, face normals, UV seams, creases, sharp edges, bevel
weights and face maps.

For properties that are already in the faces, this is implemented as a
loop. Properties that depend on edge attributes use a similar operation
to sculpt flood fill, but using face adjacency instead of edge vertex
connectivity.

As Multires also stores the face sets in the base mesh, this should work
in the face sets Multires implementation without any changes.

This is implemented as a separate operator as this resets the visibility
and creates all face sets at once, while the create face set operator
creates a single face sets, leaving the rest of the face sets in the
mesh as they are.

Reviewed By: jbakker

Differential Revision: https://developer.blender.org/D7209

Sculpt: Surface Smooth Brush and Mesh Filter

This implements the Surface Smooth Brush as a mode inside the Smooth tool,
which uses the HC algorithm from "Improved Laplacian Smoothing of Noisy Surface Meshes".
Comparted to the regular smooth brush with laplacian smooth, this brush removes
the surface while preserving the volume of the object.
The smooth result can be controlled by tweaing the original shape preservation,
displacement and iteration count.
The same surface smooth operation is also available as a mesh filter.

Reviewed By: jbakker

Differential Revision: https://developer.blender.org/D7057

Sculpt: Use uchar to store the sculpt mask in the GPU

Using a float to store and render the mask seems like a waste of memory
without any noticeable difference in the viewport for its use case.
After this commit, the mask and the face sets combined should take the
same amount of GPU memory than only the mask in previous versions.

Reviewed By: jbakker

Differential Revision: https://developer.blender.org/D7148

Fix T74780: Face sets operators not aware of SCULPT_FACE_SET_NONE

SCULPT_FACE_SET_NONE default value is 0 and it is rendered hidden, so
the invert sign operation to show it was not working. Now the show all
function sets this face set to ID 1 before setting its sign.

I also refactored this check in gpu_buffers.

Not related to the reported issue, but the mesh in attached contains non
manifold geometry with hidden loose vertices, so the visibility state
was not syncing correctly to those vertices. Now the toggle operators
checks the current visibility only on the face sets, so no manifold
vertices are ignored (as they are in the rest of operations in sculpt
mode).

Reviewed By: jbakker

Maniphest Tasks: T74780

Differential Revision: https://developer.blender.org/D7188

Fix T74761: Reimplement vertex to face sets visibility sync

This fixes multiple issues:
- Adds tag to update shading when changing vertex visibiliyt. This makes the mesh visibility update when the operator ends.
- Sync vertex to face sets no longer requires the pmap, so it does not crash. (Maybe we can initialize the pmap on undo to avoid these problems in the future).
- Sync vertex to face sets now works in a coherent way with the rest of visibility operations. Hide Box and Hide mask now sync the visibility changes to the face sets, so the all the operations are now getting a correct visibility state.

Reviewed By: brecht

Maniphest Tasks: T74761

Differential Revision: https://developer.blender.org/D7187