Add support for Opensearch 3.0

[Jakob3xD]

Description

• Add fields added by opensearch 3.0
• Test against Opensearch 3.0

Issues Resolved

Related #697

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[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 60.28%. Comparing base (06a6dc8) to head (d0a46e9).
Report is 102 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #709      +/-   ##
==========================================
+ Coverage   57.29%   60.28%   +2.99%     
==========================================
  Files         315      377      +62     
  Lines        9823    11684    +1861     
==========================================
+ Hits         5628     7044    +1416     
- Misses       2902     3205     +303     
- Partials     1293     1435     +142     

Flag	Coverage Δ
integration	52.83% <ø> (+1.99%)	⬆️
unit	14.81% <ø> (+1.96%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Files with missing lines	Coverage Δ
opensearchapi/api_cluster-state.go	82.60% <ø> (ø)
opensearchapi/api_cluster-stats.go	100.00% <ø> (ø)
opensearchapi/api_nodes-info.go	100.00% <ø> (ø)
opensearchapi/api_nodes-stats.go	100.00% <ø> (ø)
opensearchapi/api_search_shards.go	100.00% <ø> (ø)

... and 107 files with indirect coverage changes

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[dblock]

FYI I no longer work on OpenSearch full time so we need some new maintainers in this client, I'm only checking in maybe once a week.