Dock controller to gizmo data workflow and refactoring

[PrestonKnopp]

This pull request has a lot of changes.

1. Updated add-on folder structure. It's now "addons/bone_gizmo/*". When on the asset library users can download the add-on with just adding checked and it will install correctly.
2. Removed unused files.
3. Made UI responsive.
4. Added a bone finder UI that uses the current gizmo skeleton to filter and select bones by name.
5. Now adds keys to the correct bone animation tracks.
6. The dock is given a bone gizmo and uses its data. There can now be multiple BoneGizmo's in a scene. Each bone gizmo remembers it's associated edit bone and persists it's edit bone filter text.
7. Uses EditorPlugin api to allow user to select a bone gizmo node. It is then passed to the dock.
8. Dock is disabled when a bone gizmo node is not selected.

Let me know what you think. Also, if I should squash this pr let me know.