fix(agent_loader): support flat-module agents in _determine_agent_language#5235

RudrenduPaul wants to merge 2 commits intogoogle:maingoogle/adk-python:mainfrom

RudrenduPaul:fix/agent-loader-flat-module-language-detectionRudrenduPaul/adk-python:fix/agent-loader-flat-module-language-detectionCopy head branch name to clipboard