Fix T74547 EEVEE: Image texture crash with use after free

Same fix than for the other mapping types.

Fix T75144 Grease Pencil: Python generated strokes flicker and crash

This was caused by a flag not being reset in time, causing discard of
batches already queued to be drawn.

EEVEE: Bloom: Fix inverted source and base buffer

This does not change the ouput much.

GPencil: Fix overlay blend mode creating inverted colors

Fix T74663 GPencil: Fills are Flickering on Nvidia

This was caused by an unitialized variable.

Overlay: Edit Mesh: Add offset for thicker edges

Edges with sharpness, seam and bevel are thicker and thus needs more offset
to not appear aliased.

Based on D5448 by @oficsu

Overlay: Edit Mesh: Make offset depth dependent (w.r.t depth precision)

The previous offset was done in view space. It is now done in NDC space
to avoid differences when adjusting the near/far plane distances.

Cleanup: GPUShader: Remove unused shaders

GPU: Add workaround for faulty default attrib values on some drivers

On some drivers, the default values is not respected correctly.

To workaround this we create a small VBO that contains only 1 vec4 worth of
data and just bind it using glBindVertexBuffer to ensure 0 stride.

This fixes T75069 Instances not rendered correctly by workbench.

Overlay: Fix crash caused by NULL passes