[4.4] Cherry-picks for the 4.4 branch - 1st animation bugs batch

[Spartan322]

• Fixes Editing variables of properties in the animation editor can't be done #1064

Animation Bug PRs:

• Add is_inside_tree() check to SpringBoneSimulator3D godotengine/godot#104167
• Add bone name/idx matching validation and lacked virtual methods to SkeletonModifier3D godotengine/godot#104560
• Fix EditorSpinSlider Grabber Scaling godotengine/godot#105039
• Remove error print in the Animation getter. godotengine/godot#105174
• Make silhouette fixer to use arc Quaternion constructor instead of looking_at() godotengine/godot#105706
• Fix scaling from cursor in AnimationPlayer godotengine/godot#105715
• Fix rest update process by dirty flag to not take into account pose dirty flag in Skeleton3D godotengine/godot#105920
• Fix Heap buffer overflow in Animation::_find() godotengine/godot#106654
• Fix editing/removal of bone meta godotengine/godot#107546
• Fix name included in animation when saved from slice in scene importer godotengine/godot#109593

commit 6ce461e merged ahead of this pr

[Zynos-Logan]

Commit 19f342e was removed from this pr via rebase
changes pushed with lease