chore(api-metrics): clean up exports

[pichlermarc]

Which problem is this PR solving?

@opentelemetry/api-metrics exports some classes and constants that are intended for internal use. In an effort to reduce the API surface before declaring metrics GA, this PR replaces the existing wildcard exports with explicit exports.

Related: #3158

Short description of the changes

Replaces the existing wildcard exports with explicit exports and removes export for:

• NoopMeter
• NoopMetric
• NoopCounterMetric
• NoopUpDownCounterMetric
• NoopHistogramMetric
• NoopObservableMetric
• NoopObservableCounterMetric
• NoopObservableGaugeMetric
• NoopObservableUpDownCounterMetric
• NOOP_COUNTER_METRIC
• NOOP_HISTOGRAM_METRIC
• NOOP_UP_DOWN_COUNTER_METRIC
• NOOP_OBSERVABLE_COUNTER_METRIC
• NOOP_OBSERVABLE_GAUGE_METRIC
• NOOP_OBSERVABLE_UP_DOWN_COUNTER_METRIC
• NoopMeterProvider
• NOOP_METER_PROVIDER

Type of change

• Breaking change (fix or feature that would cause existing functionality to not work as expected)

How Has This Been Tested?

• Existing tests

Checklist:

• Followed the style guidelines of this project
• Unit tests have been added
• Documentation has been updated

[codecov]

Codecov Report

Merging #3198 (b59aceb) into main (4e123b5) will increase coverage by 0.00%.
The diff coverage is 100.00%.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #3198   +/-   ##
=======================================
  Coverage   93.18%   93.19%           
=======================================
  Files         195      196    +1     
  Lines        6472     6494   +22     
  Branches     1366     1371    +5     
=======================================
+ Hits         6031     6052   +21     
- Misses        441      442    +1     

Impacted Files	Coverage Δ
...ackages/opentelemetry-api-metrics/src/NoopMeter.ts	97.36% <100.00%> (+0.14%)	⬆️
...ges/opentelemetry-sdk-metrics/src/MeterProvider.ts	100.00% <100.00%> (ø)
...entelemetry-instrumentation/src/instrumentation.ts	70.37% <0.00%> (-7.41%)	⬇️
...-trace-base/src/platform/node/RandomIdGenerator.ts	87.50% <0.00%> (-6.25%)	⬇️
.../src/platform/browser/export/BatchSpanProcessor.ts	45.00% <0.00%> (ø)
...emetry-core/src/platform/node/RandomIdGenerator.ts	93.75% <0.00%> (+6.25%)	⬆️
packages/opentelemetry-resources/karma.worker.js	100.00% <0.00%> (+100.00%)	⬆️
...ckages/opentelemetry-sdk-trace-web/karma.worker.js	100.00% <0.00%> (+100.00%)	⬆️
...kages/opentelemetry-sdk-trace-base/karma.worker.js	100.00% <0.00%> (+100.00%)	⬆️

[pichlermarc]

Sorry for the force-push, something went wrong when I tried to merge main into my branch. Just removed the last commit and replaced it with a merge commit.