Adding Diff view and Split view container as Model View Editor Components (#4831)

* intial code for diff view inside model view

* Adding basic Split View Container depending on Flex Layout

* Enabled resizing between top and bottom view

* cleaning up some of the sqlops references

* Adding height as per CR comment

src/sql/workbench/api/common/sqlExtHostTypes.ts

@@ -144,6 +144,7 @@ export enum ModelComponentTypes {
 	NavContainer,
 	DivContainer,
 	FlexContainer,
+	SplitViewContainer,
 	Card,
 	InputBox,
 	DropDown,
@@ -164,6 +165,7 @@ export enum ModelComponentTypes {
 	TreeComponent,
 	FileBrowserTree,
 	Editor,
+	DiffEditor,
 	Dom,
 	Hyperlink
 }