Port most notebook model code over to be behind a service (#3068)

- Defines a new NotebookService in Azure Data Studio which will be used to interact with notebooks. Since notebooks can require per-file instantiation the provider is just used to create & track managers for a given URI.
- Inject this into notebook.component.ts and pass required parameters that'll be used to properly initialize a manger into the method. Actual initialization not done yet.
- Port over & recompile notebook model code
- Define most required APIs in sqlops.proposed.d.ts. In the future, these will be used by extensions to contribute their own providers.

src/sql/workbench/api/node/sqlExtHost.api.impl.ts

@@ -37,6 +37,7 @@ import { ExtHostModelViewDialog } from 'sql/workbench/api/node/extHostModelViewD
 import { ExtHostModelViewTreeViews } from 'sql/workbench/api/node/extHostModelViewTree';
 import { ExtHostQueryEditor } from 'sql/workbench/api/node/extHostQueryEditor';
 import { ExtHostBackgroundTaskManagement } from './extHostBackgroundTaskManagement';
+import { ExtHostNotebook } from 'sql/workbench/api/node/extHostNotebook';
 
 export interface ISqlExtensionApiFactory {
 	vsCodeFactory(extension: IExtensionDescription): typeof vscode;
@@ -73,6 +74,7 @@ export function createApiFactory(
 	const extHostDashboard = rpcProtocol.set(SqlExtHostContext.ExtHostDashboard, new ExtHostDashboard(rpcProtocol));
 	const extHostModelViewDialog = rpcProtocol.set(SqlExtHostContext.ExtHostModelViewDialog, new ExtHostModelViewDialog(rpcProtocol, extHostModelView, extHostBackgroundTaskManagement));
 	const extHostQueryEditor = rpcProtocol.set(SqlExtHostContext.ExtHostQueryEditor, new ExtHostQueryEditor(rpcProtocol));
+	const extHostNotebook = rpcProtocol.set(SqlExtHostContext.ExtHostNotebook, new ExtHostNotebook(rpcProtocol));
 
 
 	return {
@@ -402,6 +404,12 @@ export function createApiFactory(
 				}
 			};
 
+			const nb = {
+				registerNotebookProvider(provider: sqlops.nb.NotebookProvider): vscode.Disposable {
+					return extHostNotebook.registerNotebookProvider(provider);
+				}
+			};
+
 			return {
 				accounts,
 				connection,
@@ -437,7 +445,8 @@ export function createApiFactory(
 				CardType: sqlExtHostTypes.CardType,
 				Orientation: sqlExtHostTypes.Orientation,
 				SqlThemeIcon: sqlExtHostTypes.SqlThemeIcon,
-				TreeComponentItem: sqlExtHostTypes.TreeComponentItem
+				TreeComponentItem: sqlExtHostTypes.TreeComponentItem,
+				nb: nb
 			};
 		}
 	};