Support rewriting request parameters in mvc

[raccoonback]

Pull Request Description

Hello,

Currently, Spring Cloud Gateway provides a feature to replace HTTP Request Query Parameters through RewriteRequestParameterGatewayFilterFactory.
This Pull Request introduces the same functionality in spring-cloud-gateway-server-mvc, enabling developers to easily modify or replace Query Parameters in the MVC environment.

Motivation

the rewriteRequestParameter function provides a simple and concise way to modify Query Parameters, as shown below:

// Request URI: http://localhost/path?foo=bar

-> BeforeFilterFunctions.rewriteRequestParameter("foo", "replacement").apply(request);

// ServerRequest URI result: http://localhost/path?foo=replacement

This approach consolidates the process of replacing a Query Parameter into a single method call, improving code clarity and reducing boilerplate.

Current Limitation

Currently, achieving the same result in the MVC environment requires two separate operations: removing and then adding the Query Parameter:

// Request URI: http://localhost/path?foo=bar

-> ServerRequest result = BeforeFilterFunctions.removeRequestParameter("foo")
                .andThen(BeforeFilterFunctions.addRequestParameter("foo", "replacement"))
                .apply(request);

// ServerRequest URI result: http://localhost/path?foo=replacement

Proposed Solution

By introducing the rewriteRequestParameter method in MVC, developers can seamlessly handle both the removal and addition of Query Parameters in a single operation. This enhancement will:

• Simplify code by reducing multi-step operations to a single method call.
• Improve maintainability and readability for Query Parameter modification logic.

I look forward to your feedback and suggestions on this improvement.
Thanks!