Scottaj bugfix/swift5/dates in path params

[wing328]

based on #23779

PR checklist

• Read the contribution guidelines.
• Run the following to build the project and update samples:

  ./mvnw clean package || exit
  ./bin/generate-samples.sh ./bin/configs/*.yaml || exit
  ./bin/utils/export_docs_generators.sh || exit
  

  (For Windows users, please run the script in WSL)
  Commit all changed files.
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Summary by cubic

Fixes path parameter encoding in the swift5 generator so Dates and other types serialize correctly. Non-enum path params are now JSON-encoded before URL escaping to prevent malformed URLs.

• Bug Fixes
  • Updated swift5/api.mustache to pass param.encodeToJSON() into APIHelper.mapValueToPathItem; enum handling is unchanged.
  • Regenerated Swift 5 Petstore samples across all libraries.

^{Written for commit 9efa7c5. Summary will update on new commits.}