add support for luksSuspend/luksResume

[Narrat]

May come in handy for hibernation/suspending the OS without completly closing the tomb.

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Just a POC for #34 without a full close operation, but still avoiding writing the secret to places where it shouldn't be.
Not fully fleshed out, as bind mounts are ignored, operations on a suspened device are allowed.
But it is imo enough to play around with and decide if it is worth or close (or slam) is enough.

[Llewellynvdm]

Can this work?

if [[ ${#mounted_tombs[@]} -eq 0 ]]; then
	_failure "No mounted tombs found for: $tombname"
fi

[Narrat]

As a general check, yes. But it would still need to check on available/open mounts and their names in detail.

[Llewellynvdm]

Not sure if this is what we are going for

# Process bind-hooks and exec-hooks safely
if ! option_is_set -n; then
	if [[ -d "$tombmount" ]]; then
		exec_safe_bind_hooks "$tombmount" || _failure "Failed to execute bind-hooks."
		exec_safe_func_hooks open "$tombmount" || _failure "Failed to execute function hooks."
	else
		_failure "Invalid tomb mount directory: $tombmount"
	fi
fi

[Narrat]

The right direction.
I didn't look into implementing this, as the general question still needs an answer.
Does is offer some kind of benefit? The script would contain three ways to "close" a tomb. close, slam and then suspend/resume. With suspend/resume kinda in between close and slam and I'm still not sure it is a benefical addition.