mol-plugin-state: PluginStateSnapshotManager refactor

src/mol-plugin-state/animation/built-in.ts

src/mol-plugin-state/camera.ts

src/mol-plugin-state/manager/snapshots.ts

src/mol-plugin-ui/controls.tsx

src/mol-plugin-ui/state/snapshots.tsx

src/mol-plugin/behavior/static/camera.ts

src/mol-plugin/behavior/static/state.ts

src/mol-plugin/commands.ts

src/mol-plugin/context.ts

src/mol-plugin/state.ts