Notebooks: Add Support for Cell Attachment Images (#14449)

* Add to interfaces

* Works E2E

* Consolidate interface

* Add comments, cleanup

* Add some tests

* Cleanup

* interface cleanup

* Add more tests

* Add comments

* Add type for cell attachment

* wip

src/sql/workbench/services/notebook/common/contracts.ts

@@ -49,3 +49,5 @@ export enum NotebookChangeType {
 	CellOutputCleared,
 	CellMetadataUpdated
 }
+
+export const ImageMimeTypes = ['image/bmp', 'image/png', 'image/jpeg', 'image/gif'];

src/sql/workbench/services/notebook/common/localContentManager.ts

@@ -139,7 +139,8 @@ namespace v4 {
 		return {
 			cell_type: cell.cell_type,
 			source: cell.source,
-			metadata: cell.metadata
+			metadata: cell.metadata,
+			attachments: cell.attachments
 		};
 	}