chore: add e2e tests for existing functionality

[byCedric]

Linked issue

Not everything is e2e testable within vscode, but this should cover the basic functionality:

• Snapshot-tested the commands
• Trial-and-error tested the schemas through auto-completion

Additional context

vscode doesn't properly document all available testing methods, so this is basically trial and error. Let's see how CI reacts on this change :)

[github-actions[bot]]

:tada: This PR is included in version 0.8.0 :tada:

The release is available on GitHub release

Your semantic-release bot :package::rocket: