Desktop app: Beta release for OAuth login

[psrpinto]

Related to #89736 #72754 #55611

Proposed Changes

In #98345 we introduced a new OAuth login flow for the desktop app, but kept it disabled. This PR enables that flow, and issues a new beta release so that these changes can be tested before actually releasing to customers. Please see the description of #98345 for details on the changes that are being introduced.

• Enable the OAuth login flow introduced in Desktop app: Authenticate with OAuth #98345
• Skip username/password test if OAuth login is enabled
• Add test for OAuth login
• Issue a new beta release

Why are these changes being made?

Please see the description of #98345.

Testing Instructions

1. If you already have the WordPress.com Desktop app installed, open it and logout
2. Download and install the beta app for the system you're testing on (Mac, Linux, Windows)
3. Set your default browser to the one you'd like to test (Please consider testing with a browser that is not yet marked as checked in the list below)
4. Open the app
5. Click "Log in with WordPress.com"
6. The browser that you set as default in step 3. should open
7. Go through the authentication flow in the browser
8. At the end, when you click "Authorize" the app should re-open automatically, and should log you in
9. If successful, check the corresponding entry in the list below

• Mac
  • Firefox
  • Chrome
  • Safari
• Windows
  • Firefox
  • Chrome
  • Edge
• Linux
  • Firefox
  • Chrome/Chromium

Pre-merge Checklist

• Has the general commit checklist been followed? (PCYsg-hS-p2)
• Have you written new tests for your changes?
• Have you tested the feature in Simple (P9HQHe-k8-p2), Atomic (P9HQHe-jW-p2), and self-hosted Jetpack sites (PCYsg-g6b-p2)?
• Have you checked for TypeScript, React or other console errors?
• Have you used memoizing on expensive computations? More info in Memoizing with create-selector and Using memoizing selectors and Our Approach to Data
• Have we added the "[Status] String Freeze" label as soon as any new strings were ready for translation (p4TIVU-5Jq-p2)?
  • For UI changes, have we tested the change in various languages (for example, ES, PT, FR, or DE)? The length of text and words vary significantly between languages.
• For changes affecting Jetpack: Have we added the "[Status] Needs Privacy Updates" label if this pull request changes what data or activity we track or use (p4TIVU-aUh-p2)?

[github-actions]

Calypso Live (direct link)

https://calypso.live?image=registry.a8c.com/calypso/app:build-133297

Jetpack Cloud live (direct link)

https://calypso.live?image=registry.a8c.com/calypso/app:build-133297&env=jetpack

Automattic for Agencies live (direct link)

https://calypso.live?image=registry.a8c.com/calypso/app:build-133297&env=a8c-for-agencies

[wp-desktop]

WordPress Desktop CI Failure for job "wp-desktop-mac".

@psrpinto please inspect this job's build steps for breaking changes at this link. For temporal failures, you may try to "Rerun Workflow from Failed".

Please also ensure this branch is rebased off latest Calypso.

[matticbot]

This PR does not affect the size of JS and CSS bundles shipped to the user's browser.

Generated by performance advisor bot at iscalypsofastyet.com.

[matticbot]

This PR modifies the release build for the following Calypso Apps:

For info about this notification, see here: PCYsg-OT6-p2

• notifications
• wpcom-block-editor

To test WordPress.com changes, run install-plugin.sh $pluginSlug desktop/oauth-login on your sandbox.

wp-desktop ci passing, closing review