Bring back login public API (#1217)

Tested on databricks driver for the SQLTools extension. Databricks Power
Tools extension doesn't work even with 1.3 version. With this v2 API it
has the same "Connection is not valid!" issue as in 1.3.

packages/databricks-vscode-types/index.ts

@@ -12,6 +12,7 @@ export interface PublicApi {
     connectionManager: {
         onDidChangeState: Event<ConnectionState>;
 
+        login(interactive?: boolean, force?: boolean): Promise<void>;
         waitForConnect(): Promise<void>;
 
         get state(): ConnectionState;

packages/databricks-vscode/src/configuration/ConnectionManager.ts

@@ -23,6 +23,7 @@ import {Mutex} from "../locking";
 import {MetadataService} from "./auth/MetadataService";
 import {Events, Telemetry} from "../telemetry";
 import {AutoLoginSource, ManualLoginSource} from "../telemetry/constants";
+import {Barrier} from "../locking/Barrier";
 
 // eslint-disable-next-line @typescript-eslint/naming-convention
 const {NamedLogger} = logging;
@@ -59,6 +60,8 @@ export class ConnectionManager implements Disposable {
     public readonly onDidChangeSyncDestination =
         this.onDidChangeSyncDestinationEmitter.event;
 
+    private readonly initialization = new Barrier();
+
     constructor(
         private cli: CliWrapper,
         private readonly configModel: ConfigModel,
@@ -169,6 +172,7 @@ export class ConnectionManager implements Disposable {
                     this.loginWithSavedAuth.bind(this, "targetChange")
                 )
             );
+            this.initialization.resolve();
         }
     }
 
@@ -205,6 +209,14 @@ export class ConnectionManager implements Disposable {
         return this.apiClient?.config.authType;
     }
 
+    // Only used through public API
+    public async login(interactive?: boolean, force?: boolean) {
+        await this.initialization.promise;
+        if (this.state !== "CONNECTED" || force) {
+            await this.configureLogin("api");
+        }
+    }
+
     private async loginWithSavedAuth(source: AutoLoginSource) {
         const recordEvent = this.telemetry.start(Events.AUTO_LOGIN);
         try {

packages/databricks-vscode/src/locking/Barrier.ts

@@ -0,0 +1,9 @@
+export class Barrier {
+    public promise: Promise<void>;
+    public resolve: () => void = () => {};
+    constructor() {
+        this.promise = new Promise((resolve) => {
+            this.resolve = resolve;
+        });
+    }
+}

packages/databricks-vscode/src/telemetry/constants.ts

@@ -23,7 +23,11 @@ export enum Events {
 /* eslint-enable @typescript-eslint/naming-convention */
 
 export type AutoLoginSource = "init" | "hostChange" | "targetChange";
-export type ManualLoginSource = "authTypeSwitch" | "authTypeLogin" | "command";
+export type ManualLoginSource =
+    | "authTypeSwitch"
+    | "authTypeLogin"
+    | "command"
+    | "api";
 export type BundleRunResourceType = "pipelines" | "jobs";
 
 /** Documentation about all of the properties and metrics of the event. */