feat(converter-openapi): add x-adc-route-uris extension field

[bknutson123]

Support appending additional URI patterns to routes for backward compatibility with legacy endpoints like gateway.php.

Works at Path and Operation levels, with operation level taking precedence. Includes test coverage and documentation.

Description

Fixes # (issue)

Checklist

• I have explained the need for this PR and the problem it solves
• I have explained the changes or the new features added to this PR
• I have added tests corresponding to this change
• I have updated the documentation to reflect this change
• I have verified that this change is backward compatible

[CLAassistant]

Thank you for your submission! We really appreciate it. Like many open source projects, we ask that you sign our Contributor License Agreement before we can accept your contribution.
_{You have signed the CLA already but the status is still pending? Let us recheck it.}