Improve function call validation with better error handling

[xingyaoww]

This PR improves error handling in the response_to_actions function by:

1. Adding proper validation for required arguments in each tool call
2. Using FunctionCallValidationError with informative error messages
3. Removing special case handling for empty execute_bash command

The changes will help provide better error messages when required arguments are missing, making it easier to debug and fix issues with function calls.

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To run this PR locally, use the following command:

docker run -it --rm   -p 3000:3000   -v /var/run/docker.sock:/var/run/docker.sock   --add-host host.docker.internal:host-gateway   -e SANDBOX_RUNTIME_CONTAINER_IMAGE=docker.all-hands.dev/all-hands-ai/runtime:9a90439-nikolaik   --name openhands-app-9a90439   docker.all-hands.dev/all-hands-ai/openhands:9a90439