[Bug] - Replace 500 Error code with 422 for Invalid Addresses

[surbhit14]

For routes like /avs/[address], if the address is a valid Ethereum address but not an AVS address
then we get a 500 error in response

{
  "error": {
    "code": "internal_server_error",
    "message": "An internal server error occurred. Please contact our support if the problem persists.",
    "doc_url": "https://docs.eigenexplorer.com/api-reference/errors#internal_server_error"
  }
}

This should be replaced with

{
    "error": {
        "code": "unprocessable_entity",
        "message": "invalid_string: Invalid AVS Address",
        "doc_url": "https://docs.eigenexplorer.com/api-reference/errors#unprocessable_entity"
    }
}