Support Notebook integration testing by adding APIs & fixing others (#3848)

- Added `runCell` API. Updated runCell button to listen to events on the model so it'll reflect run cell when called from other sources
- Plumbed through kernelspec info to the extension side so when changed, it's updated
- Fixed bug in ConnectionProfile where it didn't copy from options but instead overrode with empty wrapper functions

Here's the rough test code (it's in the sql-vnext extension and will be out in a separate PR)
```ts

    it('Should connect to local notebook server with result 2', async function() {
        this.timeout(60000);
        let pythonNotebook = Object.assign({}, expectedNotebookContent, { metadata: { kernelspec: { name: "python3", display_name: "Python 3" }}});
        let uri = writeNotebookToFile(pythonNotebook);
        await ensureJupyterInstalled();

        let notebook = await sqlops.nb.showNotebookDocument(uri);
        should(notebook.document.cells).have.length(1);
        let ran = await notebook.runCell(notebook.document.cells[0]);
        should(ran).be.true('Notebook runCell failed');
        let cellOutputs = notebook.document.cells[0].contents.outputs;
        should(cellOutputs).have.length(1);
        let result = (<sqlops.nb.IExecuteResult>cellOutputs[0]).data['text/plain'];
        should(result).equal('2');

        try {
            // TODO support closing the editor. Right now this prompts and there's no override for this. Need to fix in core
            // Close the editor using the recommended vscode API
            //await vscode.commands.executeCommand('workbench.action.closeActiveEditor');
        }
        catch (e) {}
    });

    it('Should connect to remote spark server with result 2', async function() {
        this.timeout(240000);
        let uri = writeNotebookToFile(expectedNotebookContent);
        await ensureJupyterInstalled();

        // Given a connection to a server exists
        let connectionId = await connectToSparkIntegrationServer();

        // When I open a Spark notebook and run the cell
        let notebook = await sqlops.nb.showNotebookDocument(uri, {
            connectionId: connectionId
        });
        should(notebook.document.cells).have.length(1);
        let ran = await notebook.runCell(notebook.document.cells[0]);
        should(ran).be.true('Notebook runCell failed');

        // Then I expect to get the output result of 1+1, executed remotely against the Spark endpoint
        let cellOutputs = notebook.document.cells[0].contents.outputs;
        should(cellOutputs).have.length(4);
        let sparkResult = (<sqlops.nb.IStreamResult>cellOutputs[3]).text;
        should(sparkResult).equal('2');

        try {
            // TODO support closing the editor. Right now this prompts and there's no override for this. Need to fix in core
            // Close the editor using the recommended vscode API
            //await vscode.commands.executeCommand('workbench.action.closeActiveEditor');
        }
        catch (e) {}
    });
});
```

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

@@ -830,6 +830,7 @@ export interface INotebookModelChangedData {
 	providers: string[];
 	isDirty: boolean;
 	cells: sqlops.nb.NotebookCell[];
+	kernelSpec: sqlops.nb.IKernelSpec;
 }
 
 export interface INotebookEditorAddData {
@@ -856,6 +857,7 @@ export interface MainThreadNotebookDocumentsAndEditorsShape extends IDisposable
 	$trySaveDocument(uri: UriComponents): Thenable<boolean>;
 	$tryShowNotebookDocument(resource: UriComponents, options: INotebookShowOptions): TPromise<string>;
 	$tryApplyEdits(id: string, modelVersionId: number, edits: ISingleNotebookEditOperation[], opts: IUndoStopOptions): TPromise<boolean>;
+	$runCell(id: string, cellUri: UriComponents): TPromise<boolean>;
 }
 
 export interface ExtHostExtensionManagementShape {