add ui metadata in workflow object

[eirsep]

add ui metadata in worklfow object similar to ui metadata object present in monitor. this is required for dashboards to store metadata information

[codecov]

Codecov Report

❌ Patch coverage is 90.00000% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 73.76%. Comparing base (5ef9b55) to head (4abfb76).
⚠️ Report is 151 commits behind head on main.

Files with missing lines	Patch %	Lines
.../org/opensearch/commons/alerting/model/Workflow.kt	90.00%	0 Missing and 1 partial ⚠️

❌ Your project check has failed because the head coverage (73.76%) is below the target coverage (75.00%). You can increase the head coverage or adjust the target coverage.

Additional details and impacted files

@@             Coverage Diff              @@
##               main     #458      +/-   ##
============================================
- Coverage     73.78%   73.76%   -0.03%     
- Complexity      819      820       +1     
============================================
  Files           126      126              
  Lines          5341     5348       +7     
  Branches        675      676       +1     
============================================
+ Hits           3941     3945       +4     
- Misses         1103     1104       +1     
- Partials        297      299       +2     

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[lezzago]

There has been talks about going away from this logic since if someone creates the monitor/workflow through the api, it can never be converted to the visual mode even if the visual mode would support that configuration.