feat(metrics): add instrument validation to InstrumentBuilder.

[TommyCpp]

• spec describes some general rules on instrument configurations. This PR adds those validations and throws errors when any of them fails.
• Fix document on some functions in InstrumentBuilder

[codecov]

Codecov Report

Base: 66.7% // Head: 66.9% // Increases project coverage by +0.2% 🎉

Coverage data is based on head (bf02e00) compared to base (e5ef355).
Patch coverage: 94.3% of modified lines in pull request are covered.

Additional details and impacted files

@@           Coverage Diff           @@
##            main    #884     +/-   ##
=======================================
+ Coverage   66.7%   66.9%   +0.2%     
=======================================
  Files        113     114      +1     
  Lines       8850    8913     +63     
=======================================
+ Hits        5903    5966     +63     
  Misses      2947    2947             

Impacted Files	Coverage Δ
opentelemetry-api/src/metrics/mod.rs	11.3% <0.0%> (+7.3%)	⬆️
opentelemetry-api/src/metrics/instruments/mod.rs	98.2% <97.8%> (ø)
opentelemetry-api/src/testing/trace.rs	42.1% <100.0%> (ø)
opentelemetry-api/src/trace/span_context.rs	87.3% <100.0%> (ø)

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[jtescher]

Looks great