refactor!: Separate `Client` and `Provider` metadata, add client creation tests

[maxveldink]

This PR

• Separates the Metadata class into ClientMetadata and ProviderMetadata structs that explicitly call out the required fields.
• Adds tests demonstrating the client creation requirements are met from the spec
• I noticed that we were still pulling in concurrent-ruby but no longer using it for the concurrent Array primitive. Removed that as well

Follow-up Tasks

Move on to testing client flag evaluation testing

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 99.42%. Comparing base (f8e016f) to head (4f0cb23).

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #116 +/- ## ========================================== - Coverage 99.44% 99.42% -0.02% ========================================== Files 13 14 +1 Lines 180 174 -6 ========================================== - Hits 179 173 -6 Misses 1 1 ```

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