Open restart nudge if user triggers update check after closing it

[wojtekn]

Related to #277

Proposed Changes

When there is a new Studio version, Studio asks if user wants to upgrade. If they choose 'Later', and then try using 'Check for Updates' option, nothing will happen.

I propose to add a restart nudge in such a case to ensure that users get feedback when they use 'Check for Updates' again.

Testing Instructions

1. Apply patch to simulate downloading restart:

diff --git a/src/updates.ts b/src/updates.ts
index 504b48a..27ec600 100644
--- a/src/updates.ts
+++ b/src/updates.ts
@@ -48,6 +48,10 @@ export function setupUpdates() {
 	} );
 
 	autoUpdater.on( 'update-not-available', async () => {
+		updaterState = 'waiting-for-restart';
+		console.log( 'Faking downloading new version' );
+		return await showUpdateReadyToInstallNotice();
+
 		if ( showManualCheckDialogs ) {
 			await showUpdateUnavailableNotice();
 		}

2. Start Studio npm start
3. Click 'Check for Updates'
4. Confirm that dialog was displayed and 'Faking downloading new version' was logged
5. Click 'Later'
6. Click 'Check for Updates'
7. Confirm that dialog was displayed and 'Update has been already downloaded, proposing to restart again' was logged

Pre-merge Checklist

• Have you checked for TypeScript, React or other console errors?

[katinthehatsite]

I tested this against the flow on trunk and I think the user experience is better with this implementation.