Ensure PendingWithoutReason can detect violations inside shared groups

[robinaugh]

This fixes #1756 by allowing PendingWithoutReason to flag violations that are inside shared groups (i.e. shared_examples).

I've confirmed that this change can also support the other edge case mentioned in #1756 (using Papertrail's with_versioning helper and other arbitrary blocks) if my project configuration is updated to map that helper as if it is a shared group, i.e.

RSpec:
  Language:
    SharedGroups:
      Examples:
        - with_versioning

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Before submitting the PR make sure the following are checked:

• Feature branch is up-to-date with master (if not - rebase it).
• Squashed related commits together.
• Added tests.
• Updated documentation.
• Added an entry to the CHANGELOG.md if the new code introduces user-observable changes.
• The build (bundle exec rake) passes (be sure to run this locally, since it may produce updated documentation that you will need to commit).

[pirj]

Please add a changeling entry and this is good to go. Thank you!

[ydah]

Thank you!