feat(sdk-trace-base): replace SpanAttributes with Attributes

[david-luna]

Which problem is this PR solving?

Replaces SpanAttributes with Attributes

Refs #4175

Short description of the changes

Replace the interfaces in sources & tests. This PR targeting next since the version bump of @opentelemetry/api package makes it a breaking change.

How Has This Been Tested?

Ran the test suite for the SDK trace base.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 93.94%. Comparing base (32564ad) to head (c649c4b).
Report is 2 commits behind head on next.

Additional details and impacted files

@@            Coverage Diff             @@
##             next    #5009      +/-   ##
==========================================
- Coverage   93.96%   93.94%   -0.02%     
==========================================
  Files         310      310              
  Lines        8147     8147              
  Branches     1630     1630              
==========================================
- Hits         7655     7654       -1     
- Misses        492      493       +1     

Files with missing lines	Coverage Δ
...ckages/opentelemetry-sdk-trace-base/src/Sampler.ts	100.00% <ø> (ø)
packages/opentelemetry-sdk-trace-base/src/Span.ts	97.57% <100.00%> (ø)
...y-sdk-trace-base/src/sampler/ParentBasedSampler.ts	83.87% <ø> (ø)

... and 1 file with indirect coverage changes