EEVEE: Add support for material AOVs

During rendering up to 8 AOVs are supported. The implementation in D7010
used to many resources and was limitted. In this implementation the
resources are 1 accum texture and 1 ubo of 48 bytes per AOV to render so
we could remove this limitation.

Not supported yet is world shader AOV's. This could become the next
target.

GPU: Added support for AOV Output node.

Not connected to anything in EEVEE.

EEVEE-AOV: Data management + UI

- Adds a ViewLayerAOV
- Add layer kernel functions to modify and validate AOVs
- Add Operators to add/remove AOV
- Enable the AOV panel for EEVEE
- Enable the AOV render pass selection in the viewport.

Note that no changes have been made to EEVEE yet.

Version: Blender 2.90.1 release

Fix T81002: Images drawn with the Python gpu module no longer draw on top in the Image Editor

Since {D8234} the image editor is drawn using a depth buffer.
When using `draw_texture_2d` the image is drawn using the 2D_IMAGE
shader. inside the vertex buffer the image was pushed to the background.
This was introduced by {648924333234} what seems to be out dated as we
have done several overhauls in this area. (workbench refactor, overlay
engine refactor, color management pipeline).

This patch removes the pushing of the image to the background.

Fix T80915: Image editor only displays the first frame during 'Viewport render animation'

During viewport render animation the gpu textures weren't tagged as
invalid. As the image uv editor now draws the gpu texture only the first
was shown as it wasn't refreshed with the actual image data.

Fix T80931: Proporional Editing Cursor Draws Incorrect

The incorrect view was setup so it was drawn in pixel space. This patch
changes it to use UV space.

Version: Blender 2.90.1 Beta

Cleanup: correct naming IMAGE_Z_DEPTH

IMAGE_DEPTH is used for bit depth.

Fix T80927: UV Edges Not Visible When Repeat Image Active

When repeat image was active the image was drawn in the foreground
making most uv overlays not visible. This change creates a shared
defined value for repeating and not repeating images.