This module defines the following functions.
jegp_cpp2_target(<target>)
This function enables the target to compile its Cpp2 source files.
The target's SOURCES property is inspected for Cpp2 source files.
Corresponding Cpp1 source files are generated and added as sources to the target.
jegp_cpp2_target_sources()
target_sources for Cpp2 source files.
For each argument that is a Cpp2 source file,
sets up the generation of its Cpp1 source file under CMAKE_CURRENT_BINARY_DIR, and
replaces it with the generated Cpp1 source file
before finally forwarding to target_sources.