scripts: build: update gen_relocate_app.py to use new argument separators

Update gen_relocate_app.py to use "|" to separate code relocation
directives, and ";" to separate multiple files in a relocation directive.
This will enable multiple files to be passed to zephyr_code_relocate,
as well as multiple files to be passed from a CMake generator expression.
The script will then seperate these files and relocate each according to
the arguments given to zephyr_code_relocate.

Note! This commit will break support for zephyr_code_relocate until
the CMake function is updated

Signed-off-by: Daniel DeGrasse <daniel.degrasse@nxp.com>