compile_commands.json

We should write out a compile_commands.json for packages built with FIRE. This file allows for the IDE to provide C++ language support with ROS2 symbols enabled.

It should be fairly straight-forward to generate this file since CMake can automatically do this with CMAKE_EXPORT_COMPILE_COMMANDS. However, the file this puts out will be in the context of the build sandbox and not the actual filesystem. We'll likely need to rewrite some paths to make this work as intended.