otelconf: add meter provider internal funcs

[codeboten]

This adds the internal functions to configure meter provider. No public API yet, part of splitting #8026

Most of this code is copied from v0.3.0, updated to support v1.0.0, and also updated to return more meaningfully typed errors.

Follow up to #8089

[codecov]

Codecov Report

❌ Patch coverage is 87.35294% with 43 lines in your changes missing coverage. Please review.
✅ Project coverage is 80.8%. Comparing base (f5ba341) to head (420cdab).
⚠️ Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
otelconf/metric.go	87.3%	32 Missing and 11 partials ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##            main   #8094     +/-   ##
=======================================
+ Coverage   80.7%   80.8%   +0.1%     
=======================================
  Files        193     194      +1     
  Lines      12625   12965    +340     
=======================================
+ Hits       10189   10486    +297     
- Misses      2073    2105     +32     
- Partials     363     374     +11     

Files with missing lines	Coverage Δ
otelconf/config_common.go	85.7% <ø> (ø)
otelconf/metric.go	87.3% <87.3%> (ø)

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