fix: preserve augmented request json args

[brickfrog]

Preserves native JSON args in format_augmented_request by copying the FieldMap through each_json and using RequestArgs::from_values for the augmented request. Adds transport regressions for array, object, and string arg round-trips.\n\nVerification: moon test --target native && moon run src/bin/choir_lint --target native passed (2266/2266 tests).

Verification

Generated by Choir from commands executed in the leaf workspace.

• moon test --target native
  • exit: 0
  • head: 2a15cd0
  • output tail:

----- BEG4
IN MOON TEST RESULT -----
{"type":"start","file":"exec_test.mbt","index":9}
----- END MOON TEST RESULT -----
Total tests: 2266, passed: 2266, failed: 0.

• moon run src/bin/choir_lint --target native
  • exit: 0
  • head: 2a15cd0

[brickfrog]

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