This commit relocates the CMSIS-Core(M) Include directory that
currently resides directly under ext/hal/cmsis directory to its own
directory, Core, in order to allow other CMSIS variants to be added.
The name of CMSIS-Core(M) directory, Core, is following the original
name used by the upstream CMSIS repository.
For more details, see issue #19717.
Signed-off-by: Stephanos Ioannidis <root@stephanos.io>
