Add GitHub Action to build PR

[evidolob]

This Action only build PR, for three main OS.

[joshuawilson]

Do we still need Travis running for PRs if we are going to use github actions?

[evidolob]

At the end, we do not need Travis, but now it is used for release vscode-yaml to npm registry. I'm not sure why, maybe @gorkem can answer? I keep travis only for that release.

[joshuawilson]

Can we turn it off for PRs? But keep it for release?

[gorkem]

Looks like there is a test failing on wins.

[evidolob]

Looks like there is a test failing on wins.

Yes, I'm looking on it

[evidolob]

Can we turn it off for PRs? But keep it for release?

Yes I think, but I still don't know why we release vscode extension on npm registry. So maybe we can remove travis at all?
@gorkem WDYT?

[JPinkney]

I couldn't find out why it was done originally but people have asked for it to be updated before: #283

[evidolob]

OK, then, will keep travis for release, and remove it from building PR.

I have plan to move release to GH Actions as separate workflow, in separate PR.

[joshuawilson]

Maybe we need travis on the PR so we know that the release will pass?
As for npm, I think it might be to provide types since you can't get that from the API.