Add python message generation

[azeey]

🎉 New feature

Summary

Uses the new message generation framework to generate protobuf python files. This will be used by gazebosim/gz-transport#411. Since we won't be concerned with ABI issues for python files, I think it would be okay to provide binary distributions for the generated files.

Test it

Checklist

• Signed all commits for DCO
• Added tests
• Added example and/or tutorial
• Updated documentation (as needed)
• Updated migration guide (as needed)
• Consider updating Python bindings (if the library has them)
• codecheck passed (See contributing)
• All tests passed (See test coverage)
• While waiting for a review on your PR, please help review another open pull request to support the maintainers

Note to maintainers: Remember to use Squash-Merge and edit the commit message to match the pull request summary while retaining Signed-off-by messages.

[codecov]

Codecov Report

Merging #355 (62844f1) into main (16de9ef) will not change coverage.
The diff coverage is n/a.

❗ Current head 62844f1 differs from pull request most recent head 5e87462. Consider uploading reports for the commit 5e87462 to get more accurate results

@@           Coverage Diff           @@
##             main     #355   +/-   ##
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  Coverage   96.89%   96.89%           
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  Files          28       28           
  Lines        1064     1064           
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  Hits         1031     1031           
  Misses         33       33           

[ahcorde]

Suggested change

	# GENERATE_PYTHON - generates python code for the message if specified
	# One value arguments:
	# MSGS_GEN_SCRIPT - Path to the message generation python script
	# PROTO_PACKAGE - Protobuf package the file belongs to (e.g. "gz.msgs")
	# PROTOC_EXEC - Path to protoc
	# GZ_PROTOC_PLUGIN - Path to the gazebo-specific protobuf compiler executable
	# INPUT_PROTO - Path to the input .proto file
	# OUTPUT_CPP_DIR - Path where C++ files are saved
	# OUTPUT_PYTHON_DIR - Path where Python files are saved
	# OUTPUT_INCLUDES - A CMake variable name containing a list that the C++ header path should be appended to
	# OUTPUT_CPP_HH_VAR - A CMake variable name containing a list generated headers should be appended to
	# OUTPUT_DETAIL_CPP_HH_VAR - A CMake variable name containing a list that the C++ detail headers should be appended to
	# OUTPUT_CPP_CC_VAR - A Cmake variable name containing a list that the C++ source files should be appended to
	# OUTPUT_PYTHON_VAR - A Cmake variable name containing a list that the python file should be appended to
	# GENERATE_PYTHON - generates python code for the message if specified
	# One value arguments:
	# MSGS_GEN_SCRIPT - Path to the message generation python script
	# PROTO_PACKAGE - Protobuf package the file belongs to (e.g. "gz.msgs")
	# PROTOC_EXEC - Path to protoc
	# GZ_PROTOC_PLUGIN - Path to the gazebo-specific protobuf compiler executable
	# INPUT_PROTO - Path to the input .proto file
	# OUTPUT_CPP_DIR - Path where C++ files are saved
	# OUTPUT_PYTHON_DIR - Path where Python files are saved
	# OUTPUT_INCLUDES - A CMake variable name containing a list that the C++ header path should be appended to
	# OUTPUT_CPP_HH_VAR - A CMake variable name containing a list generated headers should be appended to
	# OUTPUT_DETAIL_CPP_HH_VAR - A CMake variable name containing a list that the C++ detail headers should be appended to
	# OUTPUT_CPP_CC_VAR - A Cmake variable name containing a list that the C++ source files should be appended to
	# OUTPUT_PYTHON_VAR - A Cmake variable name containing a list that the python file should be appended to

[ahcorde]

Suggested change

	# Copyright (C) 2022 Open Source Robotics Foundation
	# Copyright (C) 2023 Open Source Robotics Foundation

[azeey]

Closing since #362 is sufficient.