feat: add metrics bindings

[JebastineE]

Summary

Adds Java bindings for Roc sender and receiver metrics.

Changes

• Add RocSender.query(Slot) metrics binding
• Add RocReceiver.query(Slot) metrics binding
• Add RocSenderMetrics
• Add RocReceiverMetrics
• Add RocConnectionMetrics
• Implement JNI bindings for roc_sender_query() and roc_receiver_query()
• Add sender and receiver tests
• Regenerate JNI headers

Validation

• spotlessCheck passed
• compileJava passed
• compileTestJava passed
• javadoc passed
• git diff --check passed

The full native build/test could not be run locally because CMake is not installed on the development machine.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 91.68%. Comparing base (c591202) to head (ece2d70).

Additional details and impacted files

@@             Coverage Diff              @@
##               main     #142      +/-   ##
============================================
+ Coverage     90.97%   91.68%   +0.70%     
- Complexity      113      121       +8     
============================================
  Files            34       37       +3     
  Lines           410      445      +35     
  Branches          4        6       +2     
============================================
+ Hits            373      408      +35     
  Misses           33       33              
  Partials          4        4              

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