Blender Git Loki

Fix T65671: Armature X-Mirror inconsistencies

Apparently the `rna_Armature_editbone_transform_update` function was incomplete because it didn't copy all mirrored transform values.

I also noticed that the same logic seen in `rna_Armature_editbone_transform_update` is also seen in `ED_armature_edit_transform_mirror_update`.
So the solution is expose and use that logic that updates a mirrored bone. Thus deduplicating and fixing T65671.

Reviewers: brecht, zeddb

Differential Revision: https://developer.blender.org/D5058