fix(output): Ignore sync errors in excluded directories

[blorente]

Checklist

• I have filed an issue about this change and discussed potential changes with the maintainers.
• I have received the approval from the maintainers to make this change.
• This is not a stylistic, refactoring, or cleanup change.

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Discussion thread for this change

Issue number: N/A

Description of this change

Even if a directory is excluded, Bazel can try to read it and issue
errors during sync. We should ignore Bazel errors that come from
excluded packages.

Implementation details:

• We create a new issue category, IGNORE.
• We modify the relevant BlazeIssueParsers to hold references to workspaceRoot and the projectViewSet
• When parsing an issue, if the issue happens in an excluded package or directory or label, we emit it as IGNORE.

[agluszak]

Code-wise LGTM, but feature-wise I don't feel confident enough to approve it

[blorente]

@agluszak fair enough, thanks for taking a look! It is a potentially confusing change to the UX, I appreciate the thoughtfulness.

I'll ping @tpasternak and @mai93 to see if they want the feature, otherwise I'm happy to close the PR.

[blorente]

Synced with @tpasternak online. We'll hold off on landing this because it might hide legitimate errors in third party dependencies.

Our use-case for this is pretty niche (we use it for projects with both Bazel and CMake builds in the same repo), but the right solution is probably to expose another extension point for issue parsers. I'm not going to do that in this PR, so closing this one.