Add support for Vector Search Endpoints

[alexott]

Changes

Added initial support for Databricks Vector Search endpoints that are the base for adding Vector Search Indexes.

It's not clear about adding an integration test - the provisioning of the endpoints is quite a long process (~25-30 minutes).

Tests

• make test run locally
• relevant change in docs/ folder
• covered with integration tests in internal/acceptance
• relevant acceptance tests are passing
• using Go SDK

[mgyucht]

Thanks! A couple small nits.

How do we want to deal with the very long-running integration test?

[codecov-commenter]

Codecov Report

Attention: 10 lines in your changes are missing coverage. Please review.

Comparison is base (4213468) 83.57% compared to head (ca5bc0d) 83.57%.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #3191   +/-   ##
=======================================
  Coverage   83.57%   83.57%           
=======================================
  Files         168      169    +1     
  Lines       15083    15132   +49     
=======================================
+ Hits        12606    12647   +41     
- Misses       1736     1740    +4     
- Partials      741      745    +4     

Files	Coverage Δ
provider/provider.go	94.47% <100.00%> (+0.03%)	⬆️
vectorsearch/resource_vector_search_endpoint.go	79.16% <79.16%> (ø)

... and 1 file with indirect coverage changes

[tanmay-db]

Overall LGTM, left some comments.