Currently IDF_VERSION_* variables are not available to the component
CMakeLists.txt files at the requirements expansion stage. This makes
it harder to write component CMakeLists files compatible with
different IDF versions.
Include version.cmake from the requirements expansion script, add a
build system test.
!4452 simplified early expansion by using an early expansion script that
only does one thing: get the public and private requirements for each
component, albeit one by one. This was also dependent on parsing
the command output of the expansion script. This commit makes it so that a list of all
components to be processed to passed to the expansion script, generating a cmake
file that sets each component requirements in one go.
This also makes sure that only components that registered themselves get
included in the final build list.