luks_device: make key add/removal idempotent

[felixfontein]

SUMMARY

• The new_keyfile currently adds a new key, no matter whether the key is already present or not.
• The remove_keyfile currently dies when the key is not present.

To implement this properly (especially with #52371, allow_to_remove_last_key, in mind), we need a mechanism which can detect if a key is already there. If the device is closed, one could try to open it (and on success close it again); that would probably be an acceptable hack. That doesn't work when the device is already open, though.

(Migration of ansible/ansible#52409; existing PR ansible/ansible#65937, CC @mulatinho)

COMPONENT NAME

luks_device

ISSUE TYPE

• Feature Idea

[felixfontein]

@mulatinho would be great if you could migrate the PR to this collection! If you need help, just ask :)

[mulatinho]

@felixfontein hey! lots of things changed here :D I really want to participate more, I think now I am fully established on my new company and probably I will have more time! I will try to see how things are working now here and try finally work more on the group, thanks for reminder me!