[code] complete validations of extensions in .gitpod.yml

[akosyakov]

What it does

• fix [code] validate that uninstalled no sync extensions are removed from .gitpod.yml #4642

Change in Gitpod Code: gitpod-io/openvscode-server@d876a1d

There are now following validations and quick fixes:

Check	Quick Fixes
Deprecated user uploaded extensions	Resolve them against Open VSX
Extensions cannot be found in Open VSX	Remove from .gitpod.yml or search for them in Open VSX
Extensions URLs cannot be resolved to valid VSIX files	N/A
Extensions is installed for the workspace but missing in .gitpod.yml	Add to .gitpod.yml or uninstall
Extensions is uninstalled but present in .gitpod.yml	Remove from .gitpod.yml or install as no synced

How to test

• Start a workspace: https://ak-deprecate-user-extensions.staging.gitpod-dev.com/#https://github.com/akosyakov/parcel-demo
• Create gitpod.yml with user uploaded extension records for instance:

vscode:
  extensions:
    - [email protected]:UATTe2sTFfCYWQ3jw4IRsw==
    - [email protected]:ZnPmyF/Pb8AIWeCqc83gPw==
    - [email protected]:j58HdmA0K7d9a9sEkogZNw==
    - [email protected]:uXdjV53wtoTevFK6HOh3pQ==
    - [email protected]:QEP7gdWtMuY+j8RZ5OLDkA==
    - [email protected]:yEx8nRSXlfXAHqsbkTJpdA==
    - [email protected]:Z3iqHRuIxskc0nruY4MpEQ==
    - https://github.com/golang/vscode-go/releases/download/v0.26.0/go-0.26.0.vsix
    - https://github.com/golang/vscode-go/releases/download2/v0.26.0/go-0.26.222.vsix

• Play with it, try to install and uninstall some extensions, and check that validations (quick fixes) pop up as described above.

[akosyakov]

superseded #4646