* perf(sqllab): Rendering perf improvement using immutable state
- keep queryEditors immutable during active state
- add unsavedQueryEditor to store all active changes
- refactor each component to subscribe the related unsaved editor state only
* revert ISaveableDatasource type cast
* missing trigger prop
* a default of an empty object and optional operator
* Moving entire split save btn PR
* Addressed review comments
* Remove arbitrary div from ErrorBoundary in Chart
* Added accidentally removed comment
* Fix act errors in SaveQuery tests
* Fix SaveDatasetActionButton test
* SaveDatasetModal test almost working
* SaveDatasetModal tests all passing
* Clean SaveDatasetModal test
* Fix create chart button and SaveDatasetModal text in SQL Lab
* Fix untitled dataset name on SaveDatasetModal in explore
* Fix styling on split save button