refactor: remove deprecated 0.7.0 code

These changes are part of the planned deprecation cycle announced in 0.8.0,
with the deprecated classes scheduled for removal in 0.9.0

- Delete WebFluxSseServerTransport, WebMvcSseServerTransport, StdioServerTransport, and HttpServletSseServerTransport
- Remove deprecated interfaces: ServerMcpTransport, ClientMcpTransport
- Delete DefaultMcpSession implementation
- Remove all deprecated test classes for the removed implementations
- Update references to use McpServerTransport and McpClientTransport interfaces
- Split MockMcpTransport into client and server implementations
  * Rename MockMcpTransport to MockMcpClientTransport in mcp/src/test
  * Create new MockMcpServerTransport implementation
  * Add MockMcpServerTransportProvider for server tests
  * Mark MockMcpTransport in mcp-test module as deprecated
  * Update all test classes to use the new implementations

Signed-off-by: Christian Tzolov <christian.tzolov@broadcom.com>