message: improve macro hygiene in message and constructor selector namespace types
diff: @@ -171,7 +171,7 @@ impl Dispatch<'_> {
  // - The `ID` const parameter uniquely identifies one of the ink! messages
  // implemented by the root smart contract.
  #[doc(hidden)]
  - pub struct #message_namespace<const ID: u32> {}
  + pub struct #message_namespace<const ID: ::core::primitive::u32> {}
  // Selector namespace for ink! constructors of the root smart contract.
  //
  @@ -182,7 +182,7 @@ impl Dispatch<'_> {
  // - The `ID` const parameter uniquely identifies one of the ink! constructors
  // implemented by the root smart contract.
  #[doc(hidden)]
  - pub struct #constructor_namespace<const ID: u32> {}
  + pub struct #constructor_namespace<const ID: ::core::primitive::u32> {}
  }
  }
  