Fix span kind being always internal

[cijothomas]

Fixes #1575
Also adds slightly better test coverage. The whole testing needs to be revisited to ensure we have sufficient coverage, this PR is just adding the minimal test addition only.

Merge requirement checklist

• CONTRIBUTING guidelines followed
• Unit tests added/updated (if applicable)
• Appropriate CHANGELOG.md files updated for non-trivial, user-facing changes
• Changes in public API reviewed (if applicable)

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 67.3%. Comparing base (ab9415a) to head (c26a807).

Additional details and impacted files

@@           Coverage Diff           @@
##            main   #1576     +/-   ##
=======================================
+ Coverage   66.8%   67.3%   +0.4%     
=======================================
  Files        138     138             
  Lines      19290   19346     +56     
=======================================
+ Hits       12903   13029    +126     
+ Misses      6387    6317     -70     

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[cijothomas]

Going to do a .1 release shortly with this change.

[cijothomas]

Going to do a .1 release shortly with this change.

@hdost @TommyCpp
I'll attempt to do this, also to validate that I have permissions to push to crates.io!