Feature request: decorate messages in vscode-lit-plugin with plugin name

[djlauk]

While reviewing some code I looked at vscode's "problems" view and noticed, that the messages the lit-plugin extension adds do not have an indicator where they come from. In this screenshot you can see, how other plugins add such information:

(Notice the decorators "eslint(...)", "ts-styled-plugin(...)", and "ts(...)".)

In this particular case it would have helped me to quicker identify, which vscode plugin my coworker is missing.

[runem]

Thanks for reporting this :-)

In order to align with eslint, diagnostics will end up with this naming convention: lit-plugin(no-expressionless-property-binding).

[runem]

It will look like this in the future:

[djlauk]

Looks great. Thank you so much!