secure_storage: add a global registry header file for PSA key IDs

We need to make sure that within Zephyr different users of the PSA APIs
don't interfere with each other because of using the same numerical IDs
for persistent assets.

This takes care of the PSA key IDs when using persistent keys through
the PSA Crypto API.
See the comments in `<zephyr/psa/key_ids.h>` for more information.

This removes the recently-introduced Kconfig options that allowed changing
the base IDs subsystems were using for their persistent keys.

Signed-off-by: Tomi Fontanilles <tomi.fontanilles@nordicsemi.no>