PoC to integrate OpenSearch as the third search engine

[mkr]

Description

Motivation and Context

How Has This Been Tested?

Screenshots or GIFs (if appropriate):

Types of changes

• [] Bug fix (non-breaking change which fixes an issue)
• [] Improvement (non-breaking change which improves existing functionality)
• [] New feature (non-breaking change which adds new functionality)
• [] Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• [] My code follows the code style of this project.
• [] My change requires a change to the documentation.
• [] I have updated the documentation accordingly.
• [] I have read the CONTRIBUTING document.
• [] I have added tests to cover my changes.
• [] All new and existing tests passed.

[epugh]

It should say "Using OS 1" or maybe "Using OpenSearch 1"... and if you change settings then it bumps it to "Using OpenSearch 2"...

[epugh]

The explian query dialog shows some additionald debugging info, and it needs a smarter error message! since this is with OS.

[epugh]

@mkr we should think about using the SearchEngineFilter in more places to localize which search engine name we are showing in our messages... We have solr/es hardcoded, and now have added os... Wonder if we should use this filter instead?