feat(cli): expand agent command handling with new test and conversation features

- Added new source files for test commands and conversation tests to the agent's command handling structure.
- Removed the obsolete GUI command handler, redirecting users to the command registry for GUI automation commands.

Benefits:
- Enhanced testing capabilities and modularity within the agent's command management, facilitating future feature additions.

src/cli/agent.cmake

@@ -36,6 +36,9 @@ set(YAZE_AGENT_SOURCES
   cli/handlers/command_handlers.cc
   cli/handlers/agent/simple_chat_command.cc
   cli/handlers/agent/general_commands.cc
+  cli/handlers/agent/test_commands.cc
+  cli/handlers/agent/conversation_test.cc
+  cli/handlers/agent/common.cc
   cli/handlers/game/overworld_inspect.cc
   cli/handlers/game/message.cc
   cli/handlers/rom/mock_rom.cc