arch: introduce `arch_stack_walk()`

An architecture can indicate that it has an implementation for
the `arch_stack_walk()` function by selecting
`ARCH_HAS_STACKWALK`.

Set the default value of `EXCEPTION_STACK_TRACE_MAX_FRAMES` to
`ARCH_STACKWALK_MAX_FRAMES` if the latter is available.

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