feat: Add OTAP metric-name filtering support

[ThomsonTan]

Change Summary

Adds metric-name filtering to the OTAP filter processor and documents how to configure it.

What issue does this PR close?

The filter exists for traces/logs signal, but remains TODO for metrics.

• Closes #NNN

How are these changes tested?

Added test and passed locally.

Are there any user-facing changes?

[codecov]

Codecov Report

❌ Patch coverage is 92.36111% with 22 lines in your changes missing coverage. Please review.
✅ Project coverage is 88.18%. Comparing base (8a0e66a) to head (29b1637).

Additional details and impacted files

@@           Coverage Diff            @@
##             main    #2777    +/-   ##
========================================
  Coverage   88.18%   88.18%            
========================================
  Files         647      648     +1     
  Lines      250275   250561   +286     
========================================
+ Hits       220693   220969   +276     
- Misses      29058    29068    +10     
  Partials      524      524            

Components	Coverage Δ
otap-dataflow	89.77% <92.36%> (+<0.01%)	⬆️
query_abstraction	80.61% <ø> (ø)
query_engine	90.75% <ø> (ø)
otel-arrow-go	52.45% <ø> (ø)
quiver	92.25% <ø> (ø)

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