Fix restore armature

The previous code used the SetActiveBone and SetActiveArmature which are
not quite the same as setting the active annotation. There can be an
active armature even though the current active annotation is a bone.
This is were the second top-level bone would add itself to the previous
bone rather than the armature; the bone was still the active annotation
node.

See Issue #13974
Add "Load Armature From Model" button in armature module

This time it uses the proper slicer's IO mechanim.

See Issue #13974
Merge branch '13974-FixArmatureRestore' into armatures

* 13974-FixArmatureRestore:
  Add "Load Armature From Model" button in armature module
  Fix restore armature
Fix compilation error for UNIX

See Issue#13974
Merge branch '13974-FixArmatureRestore' into armatures

* 13974-FixArmatureRestore:
  Fix compilation error for UNIX