Automatically include CONAN_CMAKE_TOOLCHAIN_FILE

[peter-moran]

This might seem silly, considering this generates toolchain files, but I think it would be helpful for the auto-generated toolchain file to include CONAN_CMAKE_TOOLCHAIN_FILE if the environment variable is provided.

This would allow toolchains providers who need to run additional cmake steps to include them in the CONAN_CMAKE_TOOLCHAIN_FILE, which will then help ensure that building via cmake and building via conan are the same.

In my use case, I would like to add:
set(CMAKE_TRY_COMPILE_TARGET_TYPE STATIC_LIBRARY)
conan-io/conan#4706

PS: thanks for making this toolchain generator is been very helpful

[pepe82sh]

Damn, I had no autoassign configured and received no notification at all regarding the existance of issues... Is it possible that I "accidentally" solved your issue in august? I'm not sure if I understand what you are trying to do.