Infrastructure: Switch HTML linting to GitHub Actions

[nschonni]

Moves Travis-CI job to GitHub Actions, and adds a problem matcher so errors are identified inline on the files tab of PRs

[nschonni]

@mcking65 I have keep the Travis file to make this pass, or the branch policies can be updated as I mentioned in #1548

[spectranaut]

just one question!

[spectranaut]

this is so cool can't wait to see it in action!

[spectranaut]

@mcking65 I have keep the Travis file to make this pass, or the branch policies can be updated as I mentioned in #1548

Looks like you deleted the travis file after all, what changed? Was the policy updated, should we close this? #1548

edit: Oh I see the that travis is still required below. So we have to leave in the file or update the policy still.

[mcking65]

@nschonni
I don't understand what is going on with this PR. There are no checks! Yet, travis is required. GitHub is waiting for travis to report a status, but how would it ever do so? It doesn't seem possible to merge this.

[nschonni]

@mcking65 I've rebased this and it's showing the HTML linting check now in addition to the stuck Travis one.
For the Travis part, someone with administrator access needs to go into the branch policy and mark Travis as no longer required as described in #1548

If you just want to land this and don't have the permissions to update the policy, I can leave the Travis file un-deleted, but not running anything for a future PR to delete it

[mcking65]

@nschonni
I think that's how we should do it ... reduce travis to no-op first, then delete in a separate PR.

[nschonni]

@mcking65 OK, I've made the Travis install and script no-op. It can be removed once the policy is updated, but this PR can land now

[mcking65]

thank you @nschonni!