feat(policy): add search support to ListKeys (#3558)

## Summary
- Adds ListKeys RPC search support by wiring request search into the
policy DB list query.
- Applies escaped, case-insensitive matching in the KAS key SQL path and
adds integration coverage for search behavior, wildcard literals, empty
search, whitespace handling, and pagination after filtering.

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## Summary by CodeRabbit

## Release Notes

* **New Features**
  * Search capability for KAS registry keys by key ID.
  * Search input automatically trims leading and trailing whitespace.
  * Wildcard characters in search queries are properly escaped.
  * Search results work seamlessly with existing filters and pagination.

* **Tests**
  * Added comprehensive test coverage for search functionality.

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Signed-off-by: Chris Reed <creed@virtru.com>

Author: c-r33d