EPIC Search provider support for searching within the CMS

[jakxnz]

We want to help CMS users find what they're looking for within the CMS more quickly, by introducing a new feature that can support a search provider to power that experience. This feature allows the integration of a search provider (such as Silverstripe's search service or Elastic search) into the CMS admin UI to replace/enhance the out-of-the-box CMS search tools used for wayfinding, content discovery and analytical views/reporting within the CMS. This integration should enhance the search functionality within the admin UI, primarily enabling users to quickly locate and manage content items.

Big User Story:

As a content manager, I want a search engine from my preferred search provider within the CMS admin interface, so that I can efficiently search for and manage content items and elevate analytical views and reporting needs using modernised search tools beyond what the CMS achieves out-of-the-box.

Success Measurement:

Improved search accuracy and speed within the CMS admin interface, as well as positive user feedback regarding the enhanced search capabilities and flexibility to adapt a preferred search provider.

[GuySartorelli]

Moving this to .github as it's a cross-module concern, not specific (or related?) to elemental at all.