add logging for company merge command

[bau123]

Description of change

Update company merge command to include additional logs for:

• Source Companies with subsidiaries
• Target Companies archived
• Source Companies with global_headquarters

Checklist

• Has this branch been rebased on top of the current main branch?

  Explanation

  The branch should not be stale or have conflicts at the time reviews are requested.

• Is the CircleCI build passing?

General points

Other things to check

• Make sure fixtures/test_data.yaml is maintained when updating models
• Consider the admin site when making changes to models
• Use select-/prefetch-related field lists in views and search apps, and update them when fields are added
• Make sure the README is updated e.g. when adding new environment variables

See docs/CONTRIBUTING.md for more guidelines.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 96.63%. Comparing base (945e140) to head (09d2c65).
Report is 12 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #5981   +/-   ##
=======================================
  Coverage   96.63%   96.63%           
=======================================
  Files        1084     1084           
  Lines       25420    25438   +18     
  Branches     1678     1681    +3     
=======================================
+ Hits        24564    24583   +19     
+ Misses        699      698    -1     
  Partials      157      157           

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