[Feature Anywhere] [Enhancement] Implement custom find()/findAll() for saved object loader

[ohltyler]

The new SavedObjectLoaderAugmentVis loader inherits find()/findAll() fns from SavedObjectLoader. These fns by default only allow searching on title and description fields. For this new loader, the use case is expanded to searching for objects that match a particular vis ID, or plugin resource ID.

Current behavior is just collecting all saved objects and doing post-filtering. Ideally, find()/findAll() are modified to support searching over these new fields so the filtering is done by OpenSearch for us. This can be changed in the base SavedObjectLoader, or overridden in SavedObjectLoaderAugmentVis class. Will need further investigation to decide.

[ohltyler]

Resolved in #4595 & #4608