Feat/openapi2mcp composition

[harshadixit12]

Summary

This PR makes refactoring on top of #286
Refactoring done using gemini, and copilot.

Notable changes include:

1. Use of openapi2kong.Convert inside openapi2mcp before the MCP tools are created - instead of duplication
2. Introduction of openapitools package containing the common code used in openapi2kong, and openapi2mcp
3. Test for kebab case has been moved into openapitools package - utils_test.go

Diff between the two branches in question - https://github.com/Kong/go-apiops/compare/openapi2mcp..feat/openapi2mcp-composition

[codecov-commenter]

Codecov Report

❌ Patch coverage is 58.20000% with 209 lines in your changes missing coverage. Please review.
✅ Project coverage is 64.98%. Comparing base (7284f01) to head (e494f0b).

Files with missing lines	Patch %	Lines
openapi2mcp/openapi2mcp.go	69.20%	65 Missing and 44 partials ⚠️
openapitools/utils.go	17.94%	95 Missing and 1 partial ⚠️
openapi2kong/openapi2kong.go	85.71%	0 Missing and 4 partials ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #290      +/-   ##
==========================================
- Coverage   69.82%   64.98%   -4.85%     
==========================================
  Files          24       25       +1     
  Lines        2751     3119     +368     
==========================================
+ Hits         1921     2027     +106     
- Misses        653      881     +228     
- Partials      177      211      +34     

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