Implements the GPv2 onion skinning functionality.
There are no functional changes exept for the `use_ghosts_always`
option, which has been removed. This was used to show onion
skinning in the final render.
Pull Request: https://projects.blender.org/blender/blender/pulls/119792
Adjustments to the spacing of keymap items shown in the status bar
while idle and during modal operators. Decreased space between icon
and related text makes each item have better separation.
Pull Request: https://projects.blender.org/blender/blender/pulls/120124
Instead of only referencing an existing one. This will be used for
collection exporter and presets, to make sure the operator instance
stays alive long enough for the preset to be able to be applied.
Pull Request: https://projects.blender.org/blender/blender/pulls/120034
We disable the button for a layers depending on the
state of the parent group. E.g. if the parent group is hidden
the layer button to toggle the visibility was disabled
to indicate that toggling it won't actually change the
visibility of the layer (since the whole group is hidden).
This wasn't the case for layer groups though and this
change fixes that.
