Introduce delete subcommand to `hcloud all` about cli HOT 3 OPEN

With 3b896fe being released, it is now easier to delete multiple resources at once.

I propose to let this feature request open and wait until enough user have expressed their interest to reconsider the implementation of such feature.

from cli.

@apricote Do we want to implement it? If yes, I can give it an attempt.

I'm not very familiar with the code here so if you think that this will be not be possible to implement or requires some big refactoring then please let me know.

from cli.

I'm not sure if it is a good idea to add this to the CLI, as this command is very dangerous and probably not that often used. Also it's not clear what should be deleted. All resources, even the free ones (like SSH Keys, Placement Groups and Firewalls)? Or only paid resources? How are protected resources handled? What about deletion order (Volumes might be attached to servers etc.)? Maybe we can get a third opinion on this.

For now I'd suggest a solution like this:

hcloud server list -o=noheader -o=columns=name | xargs -L1 -I{} hcloud server delete {}

from cli.