Fix Gremlin edge connection parsing to use key lookup instead of positional destructuring

[kmcginnes]

Description

Fix Gremlin edge connections query returning reversed source/target vertex types compared to openCypher.

The previous implementation used positional array destructuring to parse GraphSON g:Map responses, which assumed a specific key order. Some Gremlin servers return keys in different orders, causing source and target to be swapped.

This change uses the existing parseGMap utility to look up values by key name instead of position.

Validation

• Verified Gremlin now has the correct edge connections

Related Issues

• Resolves Gremlin discovers edge connections in the wrong direction #1491

Check List

• I confirm that my contribution is made under the terms of the Apache 2.0
  license.
• I have run pnpm checks to ensure code compiles and meets standards.
• I have run pnpm test to check if all tests are passing.
• I have covered new added functionality with unit tests if necessary.
• I have added an entry in the Changelog.md.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 63.43%. Comparing base (c5affc5) to head (c59e6c9).
⚠️ Report is 53 commits behind head on main.

Additional details and impacted files

@@             Coverage Diff             @@
##             main    #1498       +/-   ##
===========================================
+ Coverage   47.81%   63.43%   +15.62%     
===========================================
  Files         382      317       -65     
  Lines        8525     6659     -1866     
  Branches     3159     2305      -854     
===========================================
+ Hits         4076     4224      +148     
+ Misses       3070     1701     -1369     
+ Partials     1379      734      -645     

Flag	Coverage Δ
unittests	63.43% <100.00%> (+15.62%)	⬆️

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