Integrate .NET driver examples into automated build process

[kirill-stepanishin]

Integrates .NET Gremlin examples into CI to ensure they remain functional in future releases. Examples now execute automatically after integration tests and fail the build if broken.

Changes Made

• Added example execution to gremlin-dotnet-integration-tests container in docker-compose.yml
• Made server URLs and vertex labels configurable via environment variables (replaces hardcoded localhost:8182)
• Added environment detection in ModernTraversals.cs for traversal source - uses gmodern in CI, default connection locally
• Use specialized labels to isolate test data with consistent vertex labeling

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 75.52%. Comparing base (9b46b67) to head (77538e6).
⚠️ Report is 407 commits behind head on 3.7-dev.

Additional details and impacted files

@@              Coverage Diff              @@
##             3.7-dev    #3293      +/-   ##
=============================================
- Coverage      76.14%   75.52%   -0.63%     
+ Complexity     13152    13147       -5     
=============================================
  Files           1084     1092       +8     
  Lines          65160    67096    +1936     
  Branches        7285     7388     +103     
=============================================
+ Hits           49616    50674    +1058     
- Misses         12839    13802     +963     
+ Partials        2705     2620      -85     

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

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.
• 📦 JS Bundle Analysis: Save yourself from yourself by tracking and limiting bundle sizes in JS merges.