add 'fields' parameter in doc level query object.

[eirsep]

Description

Query string query supports fields parameter in percolate queries.
https://opensearch.org/docs/latest/query-dsl/full-text/query-string/#parameters
to support queries with multiple fields or wildcards in percolate query.

This enabled queries like

GET /_search
{
  "query": {
    "query_string": {
      "fields": [ "name", "description" ],
      "query": "apple AND tree"
    }
  }
}

Issues Resolved

[BUG] Unable to create doc level monitor when passing wildcard field names in query string query

[codecov]

Codecov Report

Merging #546 (9ee4c58) into main (1b98f03) will decrease coverage by 0.09%.
The diff coverage is 30.76%.

@@             Coverage Diff              @@
##               main     #546      +/-   ##
============================================
- Coverage     74.64%   74.55%   -0.09%     
  Complexity      872      872              
============================================
  Files           130      130              
  Lines          5667     5680      +13     
  Branches        697      698       +1     
============================================
+ Hits           4230     4235       +5     
- Misses         1130     1139       +9     
+ Partials        307      306       -1     

Files	Coverage Δ
...opensearch/commons/alerting/model/DocLevelQuery.kt	53.94% <30.76%> (-4.79%)	⬇️

... and 1 file with indirect coverage changes