crpc: add availability to set/get headers

[nadsella]

This pull request introduces comprehensive support for HTTP header manipulation in the CRPC Request struct, enabling developers to read, set, add, and delete headers in a structured and case-insensitive manner. It also includes extensive documentation, tests, and examples to demonstrate the new functionality.

Core Enhancements to CRPC Header Handling:

• Header Support in Request Struct:

  • Added a Header field of type http.Header to the Request struct for storing HTTP headers.
  • Updated the ServeHTTP method to populate the Header field from incoming HTTP requests.

• New Header Manipulation Methods:

  • Introduced GetHeader, SetHeader, AddHeader, and DelHeader methods for accessing and modifying headers in a case-insensitive manner. These methods ensure nil safety and use Go's textproto.CanonicalMIMEHeaderKey for canonicalization.

Documentation and Examples:

• Documentation:

  • Added CRPC Header Support documentation in HEADERS.md, detailing usage of the new header manipulation methods with examples.

• Example Code:

  • Added an example in example_headers_test.go demonstrating how to read and manipulate headers in CRPC request handlers.

Testing:

• Unit Tests:

  • Added unit tests for GetHeader, SetHeader, AddHeader, and DelHeader methods to validate their functionality, including edge cases like nil headers and case insensitivity.

• Integration Tests:

  • Added integration tests to verify that headers are correctly passed from HTTP requests to CRPC handlers and that modifications to headers are reflected in the response.

[ei09010]

what does this refers to exactly?

[ei09010]

looks nice :)