Fix T69809, T69810: sculpt gone or crashing after render

Make a distinction between flush sculpt changes for rendering, and forcing
sculpt data structures to be rebuilt after mesh changes. Also don't use PBVH
for renders.

Fix T69808: crash using custom Node.draw_label

Start happening after 9ecbd67dfb67, but code was already wrong.

Fix T61313: gravity not displayed correct when changing unit scale

Display of velocity and acceleration units should be affected by unit scale.
Arguably the behavior of the physics simulation should be for gravity to remain
constant, but such design changes are outside the scope of bug fixing. At least
the UI should correctly reflect what the physics simulation will do.

Fix T69974: crashes in .blend files where 3D viewport was split

This was caused by a missing copy of the recently adding 3D viewport shading
ID properties.

Fix part of T69728: drawing glitches with sculpt dynamic mesh preview

Depth test must default to off for drawing outside the 3D viewport and
overlays like cursors.

Fix part of T65397: accidentally assigning shortcuts gives errors

This is not a proper solution, that will come later, this avoids the main
problematic error for now.

Fix T69857: image.load() API function does not load pixels

Broke after recent changes for DNA default initialization.

Cleanup: compiler warnings

UI: don't show decorators in Remesh panel

Build: output log file to tests/log.txt when running "make test"