Rename IssuesResolver to ProjectIssuesResolver

The following discussion from !102655 (merged) should be addressed:

• @egrieff started a discussion:

  question (non-blocking): Just a thought for a follow-up maybe, but should we rename this resolver to ProjectIssuesResolver?

  I think it could reduce confusion around the various resolvers used for issues and would match what we do for group issues so then we would have both Resolver::GroupIssuesResolver and Resolver::ProjectIssuesResolver inheriting from Issues::BaseParentResolver. Wdyt?

added groupproject management label

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assigned to @mcelicalderonG

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mentioned in merge request !102806 (merged)

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Closing as this one was already merged and deployed to production

closed

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