prost: Move external tool into build-script

Author: NickeZ

messages/CMakeLists.txt

@@ -51,13 +51,6 @@ add_custom_command(
     --proto_path=${CMAKE_CURRENT_SOURCE_DIR}
     '--nanopb_out=-I${CMAKE_CURRENT_SOURCE_DIR}:${CMAKE_CURRENT_BINARY_DIR}'
     ${PROTO_FILES_ABSOLUTE}
-  # We build the Rust protobuf files here and put them straight into the crate.
-  # This way, the crate can be compiled and tested without relying on cmake environment vars.
-  # Using prost-build the normal way as part of build.rs does not work due to a cargo bug:
-  # https://github.com/danburkert/prost/issues/344#issuecomment-650721245
-  COMMAND
-  ${CMAKE_COMMAND} -E env
-    cargo run --manifest-path=${CMAKE_SOURCE_DIR}/tools/prost-build/Cargo.toml -- --messages-dir=${CMAKE_CURRENT_SOURCE_DIR} --out-dir=${CMAKE_SOURCE_DIR}/src/rust/bitbox02-rust/src/
 )
 
 add_custom_target(