Update vscode-json-languageservice to latest version

[datho7561]

Is your enhancement related to a problem? Please describe.

There are improvements that we could benefit from, such as allowing warnings to be reported on schemas instead of just errors.

Describe the solution you would like

Update vscode-json-languageservice to the latest version, 5.5.0 as of the time of writing

Describe alternatives you have considered

• Keep it as is and add the desired features in other ways
• vendor some/all of the package into vscode-yaml, which would allow

Additional context

It's not trivial, since it's a major version update, and we reference internal code, which has changed significantly

[datho7561]

I really didn't want to go through with this, so I looked into implementing schema warnings without updating vscode-json-languageservice; I couldn't figure it out. We need the schema to provide this error, but we get the schema through json-languageservice, and in validation we directly return only the errors from there. We have no control over aborting validation on a schema deemed as invalid, so I think that we can't mark it as an error in the overriden json-languageservice code then turn it into a warning in our code.