Nb/show notebooks as untitled (#6376)

* open notebooks as untitled files and removed the saving to home directory

* return just filename without extension since save is adding the .ipynb ext

* Changes to open bdc notebooks as untitled docs. Updated tests to align with the changes

* changes: not to show untitled file as dirty and cleaned up tests in notebookService

* changes to address untitled name conflicts with open editors.

* comment cleanup

src/sql/workbench/api/node/extHostNotebookDocumentsAndEditors.ts

@@ -206,6 +206,7 @@ export class ExtHostNotebookDocumentsAndEditors implements ExtHostNotebookDocume
 					options.initialContent = showOptions.initialContent;
 				}
 			}
+			options.initialDirtyState = showOptions.initialDirtyState;
 		}
 		let id = await this._proxy.$tryShowNotebookDocument(uri, options);
 		let editor = this.getEditor(id);

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

@@ -908,6 +908,7 @@ export interface INotebookShowOptions {
 	connectionProfile?: azdata.IConnectionProfile;
 	defaultKernel?: azdata.nb.IKernelSpec;
 	initialContent?: string;
+	initialDirtyState?: boolean;
 }
 
 export interface ExtHostNotebookDocumentsAndEditorsShape {