[Server] Provide custom injection functionality

[luoyue712]

Is your feature request related to a problem? Please describe.
My goal is to apply McpTool annotations to controllers, but the framework uses custom injection, similar to how ClientGateway is injected in the SDK, which prevents it from working in controllers.This type of injection typically does not occur in the Container, as it is associated with the request.

Describe the solution you'd like
Provide custom injection functionality and expose it in Builder.

Describe alternatives you've considered
Rewrite the prepareArguments method and set the ReferenceHandler in the Builder.

Additional context
sample code:

<?php
namespace app\controller;

use Mcp\Capability\Attribute\McpTool;
use support\Request;

class UserController
{
    #[McpTool(name: 'hello')]
    public function hello(Request $request)
    {
        $default_name = 'webman';
        $name = $request->get('name', $default_name);
        return 'hello ' . $name;
    }
}

[Nyholm]

The Server can be built with a PSR-11 container. If you build that container yourself (or use the one from your framework), we could allow it to detect a way to inject services in the tool like that.

I need to think how this will play with example #161

[Nyholm]

Since 0.2.0 you may use RequestContext to get the request.

Note that the RequestContext is bound to a request, it should not be added to the class. If you want to inject other services, feel free to use any PSR-11 container.

<?php
namespace app\controller;

use Mcp\Capability\Attribute\McpTool;
use Mcp\Server\RequestContext;

class UserController
{
    #[McpTool(name: 'hello')]
    public function hello(RequestContext $context)
    {
        $request = $context->getRequest();
        $default_name = 'webman';
        $name = $request->get('name', $default_name);
        return 'hello ' . $name;
    }
}