Add option to abort merge in web UI workspace view

[isc-pbarton]

resolves #895

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 50.19%. Comparing base (92156ca) to head (23f04ec).
⚠️ Report is 2 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #899   +/-   ##
=======================================
  Coverage   50.19%   50.19%           
=======================================
  Files          24       24           
  Lines        3315     3315           
=======================================
  Hits         1664     1664           
  Misses       1651     1651           

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[isc-dchui]

Also should probably update this