feat: add structured logging support with severity levels

- Add client and server-side logging capabilities with configurable severity levels
- Implement logging message notifications with DEBUG to EMERGENCY levels
- Add logging consumers for client-side log handling
- Update documentation with logging examples and configuration
- Add comprehensive tests for logging functionality
- Fix typo in README.md (notificaiotn -> notification)

- Centralize MCP method names as constants
  - Move all JSON-RPC method names to McpSchema class as static constants
  - Replace hardcoded method strings with constant references in McpAsyncClient
    and McpAsyncServer
  - Update test cases to use new method name constants

Resolves #35

README.md

@@ -16,7 +16,7 @@ The project consists of two main modules:
 
 Java implementation of the Model Context Protocol specification. It includes:
 - Synchronous and asynchronous [MCP Client](https://github.com/spring-projects-experimental/spring-ai-mcp/blob/main/mcp/README.md#client-usage-examples) and [MCP Server](https://github.com/spring-projects-experimental/spring-ai-mcp/blob/main/mcp/README.md#server-usage-examples) implementations
-- Standard MCP operations support (tool discovery, resource management, prompt handling). Support for request and notificaiotn handling.
+- Standard MCP operations support (tool discovery, resource management, prompt handling, structured logging). Support for request and notification handling.
 - [Stdio](https://spec.modelcontextprotocol.io/specification/basic/transports/#stdio) and [SSE](https://spec.modelcontextprotocol.io/specification/basic/transports/#http-with-sse) transport implementations. 
 - [Find more](./mcp/README.md).