Add per-entry ignore of NS validation failures in CI testing

[makyen]

This adds the ability to ignore NS validation failures during CI testing on a per-entry basis in the *nses.yml files. If an entry in those files has the value ignore_validation_errors: true, then validation errors will not cause CI failures.

This is primarily in order to be able to prevent CI failures due to the persistent intermittent issues with validating dns-parking.com.. This PR adds ignore_validation_errors: true to the dns-parking.com. entry in watched_nses.yml, which will result in not seeing CI testing failures when that domain fails DNS validation.

There probably should be some automated testing which still validates, and fails on, entries which have ignore_validation_errors: true, as we do want to know about such domains if they actually stop having a DNS entry. However, this PR just patches over the persistent frustration of looking at CI failures and finding that it's yet another time that dns-parking.com. had an intermittent problem. No attempt is made here to address the issue of wanting some type reporting for such domains when they actually go away.

[tripleee]

Updating the schema should also update the Schema_version at the top of the YAML file.

I never got around to properly formalizing this, but the purpose of this information is to track changes in the schema, so let's apply it here.

[tripleee]

In theory, I dislike the idea of bypassing quality checks when the quality sucks, but the DNS problems of our CI is beyond our control, so I guess let's do what we can to focus on the things we can affect. +1

[stale]

This issue has been closed because it has had no recent activity. If this is still important, please add another comment and find someone with write permissions to reopen the issue. Thank you for your contributions.

[tripleee]

I guess we still want this, even though the problem has been somewhat mitigated by other means. Sorry for being slow to review.

[makyen]

While I do intend to finish this at some point (i.e. integrate the requested changes for which I have some work along those lines), I wasn't intending to work on this at the moment. The activity today was because I managed to mistakenly delete the branch on GitHub, which automatically closed the PR. Restoring the branch on GitHub and reopening the PR re-ran CI, which, of course, had failures, due to being 13k commits behind. So, the work today was just to rebase the already pushed commits onto the current master branch.

[tripleee]

For the record, the requested change simply requires the Schema_version: key at the top of the file to get a new value.