Move the TAG definition of each example to the corresponding
source file (previously it is defined in the common example
intialization header file), which can avoid the redefinition
of TAG in some situations.
Since the scripts of CI will bypass components when trying
to get EXAMPLE_PATHS, and these BLE Mesh components will
only be used by other mesh examples, i.e. no need to be
compiled as a single example, so we rename the folder
to componnets.
