message: [model] Export EnvHandler
diff: @@ -70,7 +70,10 @@ pub use crate::{
  NoDeployArgs,
  TestableContract,
  },
  - exec_env::ExecutionEnv,
  + exec_env::{
  + EnvHandler,
  + ExecutionEnv,
  + },
  msg::Message,
  msg_handler::{
  CallData,
  