feat(opentelemetry-sdk-trace-base): add AlwaysRecordSampler

[majanjua-amzn]

Which problem is this PR solving?

Part of open-telemetry/opentelemetry-specification#4698

Introduces a way for users to access the RECORD_ONLY functionality of the sampler, as currently all available samplers either provide a RECORD_AND_SAMPLE or DROP response.

Short description of the changes

• Introduced new AlwaysRecordSampler
• Added relevant unit tests

Type of change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• This change requires a documentation update

How Has This Been Tested?

Unit tests and extensively used in aws-otel-js-instrumentation

Checklist:

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

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 95.41%. Comparing base (167185a) to head (bd73ff8).
⚠️ Report is 5 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #6168   +/-   ##
=======================================
  Coverage   95.40%   95.41%           
=======================================
  Files         317      318    +1     
  Lines        9439     9458   +19     
  Branches     2187     2190    +3     
=======================================
+ Hits         9005     9024   +19     
  Misses        434      434           

Files with missing lines	Coverage Δ
...s/sampler-always-record/src/AlwaysRecordSampler.ts	100.00% <100.00%> (ø)

... and 2 files with indirect coverage changes

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