Implement YouTube OAuth2 login

[MichailiK]

This pull request...

• Fixes a bug
• Introduces a new feature
• Improves an existing feature
• Boosts code quality or performance

Description

This PR adds a toggle to enable the OAuth2 capability found in the YouTube source manager. It also automatically stores & retrieves the refresh token for convenience of JMusicBot users (as the source manager does not do that itself.)

Quick summary of the login flow

Upon enabling OAuth2 (youtubeoauth2=true in the config.txt) the YouTube source manager will log the following:

[13:41:00] [INFO] [YoutubeOauth2Handler]: ==================================================
[13:41:00] [INFO] [YoutubeOauth2Handler]: !!! DO NOT AUTHORISE WITH YOUR MAIN ACCOUNT, USE A BURNER !!!
[13:41:00] [INFO] [YoutubeOauth2Handler]: OAUTH INTEGRATION: To give youtube-source access to your account, go to https://www.google.com/device and enter code ABC-DEF-GHI
[13:41:00] [INFO] [YoutubeOauth2Handler]: !!! DO NOT AUTHORISE WITH YOUR MAIN ACCOUNT, USE A BURNER !!!
[13:41:00] [INFO] [YoutubeOauth2Handler]: ==================================================

Navigating to https://www.google.com/device and entering the code will lead you to an OAuth2 page

(the source manager pretends to be a logged in TV client to play tracks)

Once allowed, the source manager logs a refresh token. For convenience, JMusicBot intercepts the log with a turbo filter & stores the refresh token as a file, youtubetoken.txt. The refresh token will be used when JMusicBot gets restarted to retrieve an access token.

Purpose

This should circumvent the "Sign in to confirm you're not a bot" message that people (particularly) on servers have been getting.

Relevant Issue(s)

Fixes #1588

Todo

• The GUI can't seem to log the messages from the OAuth2 handler, they always end up in stdout. Have to yet look into why

[chenchuuu]

It did not works for me. I cloned this branch and after executed run_jmusicbot.sh, in my config.txt did not appear the option youtubeoauth2

[MichailiK]

JMusicBot does not alter existing config files. You will need to manually add youtubeoauth2=true to your config.txt file.

[chenchuuu]

JMusicBot does not alter existing config files. You will need to manually add youtubeoauth2=true to your config.txt file.

I have just did it, but after executed the .sh, youtubesource did not show me this log:

[13:41:00] [INFO] [YoutubeOauth2Handler]: ==================================================
[13:41:00] [INFO] [YoutubeOauth2Handler]: !!! DO NOT AUTHORISE WITH YOUR MAIN ACCOUNT, USE A BURNER !!!
[13:41:00] [INFO] [YoutubeOauth2Handler]: OAUTH INTEGRATION: To give youtube-source access to your account, go to https://www.google.com/device and enter code ABC-DEF-GHI
[13:41:00] [INFO] [YoutubeOauth2Handler]: !!! DO NOT AUTHORISE WITH YOUR MAIN ACCOUNT, USE A BURNER !!!
[13:41:00] [INFO] [YoutubeOauth2Handler]: ==================================================