Add "stylelint.validate" option

[ota-meshi]

Which issue, if any, is this issue related to?

Closes #73

Is there anything in the PR that needs further explanation?

This PR adds "stylelint.validate" option.

[jeddy3]

@ota-meshi Thanks for your continued effort on this extension. It looks like everyone, myself included, is too busy to review your good work. That's a barrier to you pushing this extension forward. I've granted you administration rights to this repository so that you can, if you wish, merge pull requests without approval. I suggest you ensure the CI is green before you do, though.

Perhaps wait a day or so to see if @ntwb has any thoughts on this. If he doesn't, I'd recommend proceeding and releasing the extension as you would any single-contributor project.

---

I did find a little time to triage the issues in the hope it'll encourage contributions.

[ota-meshi]

@jeddy3 Thank you for taking your time to respond.

I don't mind about the time it takes to be reviewed. I understand that all the members are busy.

I don't want to merge my open PRs myself if possible.
If people expect extensions to be updated faster, I might be able to help, so let me know then.

[ntwb]

Apologies for the delay here, I’ll review and test this in the next few hours...

[ntwb]

Thanks @ota-meshi

Testing notes:

Removing css has no effect on .css files
Removing postcss removes support for .css files

I think this is related to the other reported issues around PostCSS #57

I'm not sure of if it relates to this extension directly or is a stylelint issue, as stylelint uses PostCSS for CSS, other syntax's have their own syntax's.

I'm fine for this to not be a blocker to merging this PR and am just testing a few more scenarios before merging

[kachkaev]

👋 @ota-meshi, thanks for the feature! It has allowed me to overcome stylelint/stylelint#5185 by setting "stylelint.validate": ["css", "less"] in my User’s or workspace settings.json. What I noticed though is that the same setting does not work from [project]/.vscode/settings.json in a multi-project workspace. How difficult would it be to solve this? Having the setting inside the project can help share it with the team.