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

Merging #458 (4abfb76) into main (5ef9b55) will decrease coverage by 0.03%.
The diff coverage is 90.00%.

@@             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     

Impacted Files	Coverage Δ
.../org/opensearch/commons/alerting/model/Workflow.kt	80.86% <90.00%> (-1.08%)	⬇️

[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.