Authentication Plugin API fixes

[vinokurig]

What it does

• Do not add a sign out menu if a session from given authentication provider is already exists in the authentication menu.
• Fix a bug of duplicating new session requests if more then one authentication session is present.
• Fix the sign out message if an authentication session is not stored in the account usages

How to test

1. Remove "@theia/git": "^1.5.0" from examples/browser/package.json file.
2. Download vscode-git-1.49.3 and copy it to the plugins folder.
3. Download vscode built-in github plugin and copy it to the plugins folder.
4. Download vscode GitHub Pull request plugin and copy it to the plugins folder.
5. Apply GitHub authentication provider:

• Git clone the github authentication plugin to the plugins folder.
• Paste your GitHub token to the plugin here.
• Compile the plugin. Note that errors might appear in the compilation log but it doesn't prevent the plugin from working properly.

6. Start Theia and check the accounts menu:
   
7. Run Publish to GitHub command and allow the authentication session:
   
8. Check the accounts menu:
   
9. Sign in the GitHub Pull Requests plugin:
   
10. Check the accounts menu and click the sign out item:
    
11. See the notification:
    
12. Click Yes and check the accounts menu, it must reset to the initial state:
    

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

[RomanNikitenko]

Tested the changes - it works as described in the PR description:

[RomanNikitenko]

btw: where it should be handled if a token is not valid?
I revoked my token to test such case:

Maybe some notification should be displayed for user...
Is it responsibility of VS Code plugin or should be handled on Theia side?

[vinokurig]

@RomanNikitenko
Thank you for your review. This use-case is handled by authentication provider which is registered in the GitHub authentication plugin. This is a demo plugin for theia, in Che-theia we have our own GitHub authentication provider plugin which is using Che oAuth API to retrieve tokens, instead of manually generating a token in GitHub. So even if we revoke the Che oAuth application in GitHub, the token would be stored in keycloak and would be valid for the GitHub plugins.

[azatsarynnyy]

What the command Publish to GitHub does? Publish the repository? I can't find where it's contributed from.

BTW, after executing Publish to GitHub command, there's always running "Activating ..." message

Is it expected?

[vinokurig]

@azatsarynnyy

What the command Publish to GitHub does? Publish the repository? I can't find where it's contributed from.

Publish to GitHub comes from github built-in vscode extension and it creates a repository from the workspace folder, see https://stackoverflow.com/questions/46877667/how-to-add-a-new-project-to-github-using-vs-code

BTW, after executing Publish to GitHub command, there's always running "Activating ..." message

It is expected, to make the GitHub Pull Requests plugin work you need to authenticate it separately, see item 9 of the How to test section.

[azatsarynnyy]

Thanks for the explanation @vinokurig
Everything works as described.