[WIP] feat: Improve pdata::otap::testing module and expose it to other crates

[JakeDern]

Change Summary

This is another PR on the path to #2289. During my initial implementation, I realized that a lot of tests were generating invalid otap batches. In order to make that easier, I've updated the logs/metrics/traces macros in the pdata crate to automatically fill in anything required to be spec compliant based on what's been specified. I had a half-baked version of this before, but now that we have the spec we can do this properly.

I've also added a testing feature which lets these be consumed across other crates.

What issue does this PR close?

• Part of Enforce that payloads in OtapArrowRecords conform to the spec #2289

How are these changes tested?

Unit.

Are there any user-facing changes?

No

[codecov]

Codecov Report

❌ Patch coverage is 88.99083% with 144 lines in your changes missing coverage. Please review.
✅ Project coverage is 87.55%. Comparing base (6933f8e) to head (f8cd752).
⚠️ Report is 11 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2349      +/-   ##
==========================================
- Coverage   87.57%   87.55%   -0.02%     
==========================================
  Files         571      575       +4     
  Lines      194512   196696    +2184     
==========================================
+ Hits       170346   172224    +1878     
- Misses      23640    23946     +306     
  Partials      526      526              

Components	Coverage Δ
otap-dataflow	89.54% <88.99%> (-0.06%)	⬇️
query_abstraction	80.61% <ø> (ø)
query_engine	90.61% <ø> (ø)
syslog_cef_receivers	∅ <ø> (∅)
otel-arrow-go	52.44% <ø> (ø)
quiver	91.91% <ø> (ø)

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[JakeDern]

This is a stacked diff on #2346 and most commits belong to that PR. Will publish this after that goes in