scripts: Add ksize.py and dirsize.py

scripts: Add ksize.py and dirsize.py

Fixes [YOCTO #5388]

These scripts can be useful when working to reduce the size of the Linux
kernel and the root filesystem.

ksize.py displays the kernel build size by the built-in.o files.

dirsize.py displays the various sizes of the components of the root
directory.

Signed-off-by: Darren Hart <dvhart@linux.intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>