feat: handle `style` and `explode` properties for parameters

[jakubno]

Description

Adds support for OpenAPI array parameters, especially regarding the explode and style attributes, and enhances validation and code generation for parameters in the generated client.

The most significant changes include updating the OpenAPI schema models for parameters, propagating the explode attribute through the parsing logic, and updating generated code and tests to handle non-exploded array parameters.

References:

• https://swagger.io/docs/specification/v3_0/serialization/
• https://spec.openapis.org/oas/latest.html#fixed-fields-for-use-with-schema