The previous default value of `3` made gizmos too large and cluttered the viewport, especially on smaller screens. A value of `2` seems perfectly usable and provides a more comfortable default.
Adds a new editor setting editors/animation/insert_at_current_time and a toggle button in the Animation Track Editor to let users choose whether to insert keys and markers at the current timeline cursor (when enabled) or at the mouse position (default behavior).
- Key insertion
- Paste and duplicate operations
- Editor setting persistence
- Icon by @TokageItLab
Fixes#103272
