lib: os/cbprintf: make char[] work in C++ and tagged arguments

Strings in C++ are usually of type char[] instead of char*.
Therefore, this needs to be taken into account when doing
tagged arguments or else char[] would be tagged as simple
pointer. So fix this by adding a way to get the type of
elements in an array to determine if it is a char array.

Fixes #46761

Signed-off-by: Daniel Leung <daniel.leung@intel.com>