Update Projects::BlameController to support a new parameter for using ignore_revisions_blob

Update: The work for this has been merged behind the feature flag blame_ignore_revs and rollout can be tracked in [Feature flag] Enable blame_ignore_revs (#514325 - closed)

• Update Projects::BlameController to handle a parameter for whether or not to send something in the ignore_revisions_blob field in the RawBlame rpc
  • When this parameter is true send the .git-blame-ignore-revs from the default branch (e.g refs/heads/main:.git-blame-ignore-revs)