Rename the CMake variable expected from applications from MBED_ROOT to
MBED_PATH to be consistent with the naming used for the configuration file
(MBED_CONFIG_PATH) also expected from applications.
Directories that start with special prefixes (TARGET_, FEATURE_, COMPONENT_) are added to the build based on Mbed target configuration from targets.json instead of calling utility function mbed_add_cmake_directory_if_labels().
Aside from the core mbed-os CMake target, a number of targets have been created so they can optionally be included by application executables that require them using `target_link_libraries()`.
Co-authored-by: Martin Kojtal <martin.kojtal@arm.com>
Co-authored-by: Rajkumar Kanagaraj <rajkumar.kanagaraj@arm.com>