Add indicator support to merge

[phofl]

Closes #8527

• Tests added / passed
• Passes pre-commit run --all-files

[github-actions]

Unit Test Results

See test report for an extended history of previous test failures. This is useful for diagnosing flaky tests.

    27 files  ± 0      27 suites  ±0   9h 59m 30s ⏱️ + 4m 47s
 3 997 tests + 1   3 882 ✅  - 2    110 💤 ±0  5 ❌ +3 
50 265 runs  +11  47 965 ✅ +8  2 295 💤 ±0  5 ❌ +3 

For more details on these failures, see this check.

Results for commit 591bc5b. ± Comparison against base commit 84e7c4d.

[hendrikmakait]

Thanks, @phofl!