feat: enhance endpoint response handling and add optional parameter support

[gent124]

This pull request improves the handling of OpenAPI endpoint parameter and response generation, especially for optional parameters and response schema resolution, and updates the code generation templates for better developer experience. The most significant changes are grouped below:

OpenAPI Response Handling Improvements:

• Enhanced logic in getEndpointsFromOpenAPIDoc to prefer response content entries with a schema, even if the media type is non-standard, and to fall back to the default response if the 200 status has no content but default has a JSON body. This ensures more accurate response schema inference and fixes issues with APIs that use non-standard response structures. [1] [2] [3] [4] [5]
• Adjusted test cases to reflect the improved response schema selection, ensuring that endpoints return the correct response type and description. [1] [2] [3]

Optional Parameter Handling:

• Updated getEndpointParameter to avoid duplicating .optional() on root object-shaped query/header parameters, preventing incorrect schema generation for optional object params. [1] [2]
• Added the endpointParamsAllOptional utility to check if all endpoint parameters are optional, enabling safer defaulting of parameter objects in generated code.

Code Generation Template Enhancements:

• Modified the query-use-query.hbs and query-use-infinite-query.hbs templates to use a single params object with a default value of {} when all parameters are optional, simplifying the function signature and usage for consumers. [1] [2]
• Registered a new Handlebars helper endpointParamsAllOptional to support the above template changes, and integrated it into the Handlebars helper registration logic. [1] [2] [3] [4]

These changes collectively improve the robustness and usability of the OpenAPI endpoint code generation, especially for APIs with complex or non-standard parameter and response definitions.

• Updated response handling in getEndpointsFromOpenAPIDoc to prefer schemas with body content over void responses.
• Introduced a new utility function endpointParamsAllOptional to check if all endpoint parameters are optional.
• Modified query and infinite query templates to handle optional parameters correctly.
• Added tests to verify the behavior of endpoints with default responses and optional parameters.