arch: define `struct arch_esf` and deprecate `z_arch_esf_t`

Make `struct arch_esf` compulsory for all architectures by
declaring it in the `arch_interface.h` header.

After this commit, the named struct `z_arch_esf_t` is only used
internally to generate offsets, and is slated to be removed
from the `arch_interface.h` header in the future.

Signed-off-by: Yong Cong Sin <ycsin@meta.com>