Merge remote-tracking branch 'origin/blender-v2.93-release'

Merge remote-tracking branch 'origin/master' into asset-browser-poselib

Alembic export: export UV maps on every frame

Export UV maps to Alembic on every frame. This makes the export of UV
maps consistent with mesh normals. In the case of static UV maps it may
cause a slight slowdown (since they're exported on every frame now), but
due to the deduplication performed by the Alembic library, the resulting
files will be the same size anyway.

Thanks to @CodyWinch for providing the solution to the problem, and
writing the original patch D8397.

Differential Revision: https://developer.blender.org/D8397

Merge remote-tracking branch 'origin/master' into asset-browser-poselib

Fix T87935: allow library overrides on NLA/FCurve modifiers

Mark NLA/FCurve modifier properties as library-overridable.

It was already allowed to add such modifiers to a library-overridden
object, but then the properties of those modifiers were read-only,
limiting their use.

Animation: correct active track/strip pointers after copying NLA tracks

After copying NLA tracks from one `AnimData` to another, also ensure
that the `AnimData::act_track` and `AnimData::actstrip` pointers are
pointing to the copy rather than the original.

This is a necessary step to allow library overrides on NLA modifiers
without crashing Blender.

The remapping of the pointers is done by looping over the tracks/strips
and comparing pointers. Alternatively, I could update the copy functions
themselves to keep track of those pointers and return them, but IMO that
would produce more spaghetti (they're also used in cases where this
pointer-remapping is not desired).

UI List: Fix segfault in unit tests

Fix `NULL` pointer deference in `ui_list_find_mouse_over()`.

T87757: Pose Library: glitch when starting to blend flipped pose

Fix a glitch when blending a pose by always starting blending at 0%.

Previously, the blend percentage was remembered between operator
invocations, causing the glitch.

Merge remote-tracking branch 'origin/master' into asset-browser-poselib

VSE: reset strip transform with "Set Render Size" operator

Reset the active strip offset and scale, in the "Set Render Size"
operator (`SEQUENCER_OT_rendersize`). This ensures that the active strip
will actually fit the new render size, which is what the operator is
intended to achieve.