feat: export SDK crate version as constant

[the-wondersmith]

Changes

PR adds a simple constant for the SDK crate's version (pulled directly from the crate's manifest [ref]).

This is specifically useful in conjunction with things like populating the value of telemetry.sdk.version when building a Resource (for example).

Merge requirement checklist

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

[linux-foundation-easycla]

• ✅login: the-wondersmith / (a1757fc)

The committers listed above are authorized under a signed CLA.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 77.9%. Comparing base (6cc327d) to head (a1757fc).

Additional details and impacted files

@@          Coverage Diff          @@
##            main   #2504   +/-   ##
=====================================
  Coverage   77.9%   77.9%           
=====================================
  Files        123     123           
  Lines      22887   22887           
=====================================
  Hits       17838   17838           
  Misses      5049    5049           

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.