Add databricks-impulse into SDK and Spark Connect channel user-agents

[tombonfert]

Summary

Tags Impulse's product identity onto both the SDK user-agent and the Spark Connect gRPC channel

Test Plan

• Unit tests added/updated
• Manual testing completed
• Documentation updated (if applicable)

Checklist

• Code follows project style guidelines
• Self-review completed
• No new linter warnings introduced

[codecov]

Codecov Report

❌ Patch coverage is 90.47619% with 2 lines in your changes missing coverage. Please review.
✅ Project coverage is 89.38%. Comparing base (86b5958) to head (044d3e3).

Files with missing lines	Patch %	Lines
src/impulse_query_engine/telemetry.py	90.47%	2 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##             main      #94   +/-   ##
=======================================
  Coverage   89.37%   89.38%           
=======================================
  Files          62       62           
  Lines        5544     5565   +21     
  Branches      680      682    +2     
=======================================
+ Hits         4955     4974   +19     
- Misses        466      468    +2     
  Partials      123      123           

Flag	Coverage Δ
query_engine	85.86% <90.47%> (+0.03%)	⬆️
reporting	94.25% <ø> (ø)

Flags with carried forward coverage won't be shown. Click here to find out more.

Files with missing lines	Coverage Δ
src/impulse_query_engine/telemetry.py	92.30% <90.47%> (-1.25%)	⬇️

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