[Client] Feat: Implement MCP client component (#192)

* feat(client): add complete MCP client SDK with STDIO and HTTP transports

Add Client, Builder, ClientProtocol, ClientSession, and transport
implementations for communicating with MCP servers. Supports tools, resources, prompts, and real-time progress/logging notifications.

* refactor(examples): reorganize examples into server/ and client/ folders

* feat: add SamplingRequestHandler for handling server sampling requests

* feat: add setLoggingLevel method to control server logging verbosity

* refactor: make progress token dependent on request ID

* docs: Update server IP in usage instructions and add notes on sampling server requirements.

* feat: add complete() method for completion/complete requests

* refactor: properly parse and type initialize result

* refactor: standardize method names

* fix: revert changes to server related components

* fix: revert changes to server related components

* refactor: Restructure client transports and handlers into dedicated namespaces.

* fix: cs and php-stan errors fixes(partial)

* feat: Refactor request handlers to return `Response` or `Error` objects directly, adding a `SamplingException` and error logging for sampling requests.

* feat: Replace `ClientTransportInterface` with `TransportInterface` and move response result deserialization to client methods.

* refactor: remove redundant timeout check for intialize on transports

The processFiber that executes per tick while fiber is suspended already handles timeouts while waiting

* feat: broaden symfony/http-client dependency to support Symfony 5.4 to 8.0

* Update examples/client/README.md

Co-authored-by: Christopher Hertel <mail@christopher-hertel.de>

* Update examples/client/README.md

Co-authored-by: Christopher Hertel <mail@christopher-hertel.de>

* refactor: remove outgoing message queue from session and simplify transport send method to directly dispatch messages.

* refactor: Replace ClientSession with ClientState for clearer intent on runtime state management

* refactor: rename connectAndInitialize to connect for consistency

* chore: cs fix

* chore: use SamplingCallbackInterface instead of a closure for sampling request handler

---------

Co-authored-by: Christopher Hertel <mail@christopher-hertel.de>

examples/server/bootstrap.php

@@ -55,7 +55,7 @@ function shutdown(ResponseInterface|int $result): never
 function logger(): LoggerInterface
 {
     return new class extends AbstractLogger {
-        public function log($level, Stringable|string $message, array $context = []): void
+        public function log($level, string|Stringable $message, array $context = []): void
         {
             $debug = $_SERVER['DEBUG'] ?? false;