Add `ListPackages()` to persistence service

[djjuhasz]

Refs #988

This continues the work toward #988 by adding a ListPackages() method to the persistence service that includes a count of the total search results returned (before paging), as well as allowing filtering, sorting, and paging of the search.

Other changes:

• Add a telemetry wrapper for the ListPackages() method to provide extra performance and debugging data
• Add additional commentary for the Filter.Page() method
• Add many unit tests for the ListPackages() functionality

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 68.42105% with 12 lines in your changes missing coverage. Please review.

Project coverage is 54.31%. Comparing base (e2cc8b3) to head (f69f41c). Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
internal/persistence/telemetry.go	0.00%	8 Missing :warning:
internal/persistence/ent/client/package.go	86.66%	2 Missing and 2 partials :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #1031 +/- ## ========================================== + Coverage 54.22% 54.31% +0.09% ========================================== Files 103 103 Lines 5957 5995 +38 ========================================== + Hits 3230 3256 +26 - Misses 2475 2485 +10 - Partials 252 254 +2 ```

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