core: fallback to applicationName

[vince-fugnitto]

What it does

The commit adds handling to fallback to the applicationName when setting the window title which would previously display either index.html in electron or localhost:3000 in the browser.

Before:

After:

How to test

1. for both the browser and electron example applications start the app without a workspace
2. confirm that with views open the tab or window title relects the current widget (ex: getting started, preferences, keyboard shortcuts)
3. close all open widgets
4. the title should fallback to the applicationName
5. confirm the behavior is correct with a workspace

Review checklist

• As an author, I have thoroughly tested my changes and carefully followed the review guidelines

Reminder for reviewers

• As a reviewer, I agree to behave in accordance with the review guidelines

[msujew]

Looks good to me 👍