Cleanup `hostmgr` various setup root commands

[AliSoftware]

The hostmgr command has some lesser-used and setup-related subcommands that are a bit all over the place:

Inconsistencies and spread out commands

• hostmgr set and its sole hostmgr set automatic-login-password subcommand
• hostmgr install and its sole hostmgr install hostmgr-helper subcommand
• hostmgr init, which doesn't even really do what it claims (it creates the directories where the config file should be, but doesn't create a template config file like the command description suggests), and is separate from hostmgr config (which prints the current configuration)
• hostmgr sync and its sole hostmgr sync authorized-keys subcommand

Besides, there are some other inconsistencies:

• The struct implementing the hostmgr generate command, and implemented in GenerateCommand.swift, is still named struct RunCommand instead of struct GenerateCommand

Proposed Solutions

The idea would be to move all the above commands as subcommands of a single root command, instead of having them spread out each as their own command with a single subcommand.

Proposal 1️⃣ : Move everything under hostmgr config

Old	New
hostmgr set automatic-login-password	hostmgr config set-automatic-login-password
hostmgr install hostmgr-helper	hostmgr config install-helper
hostmgr init	hostmgr config init
hostmgr config	hostmgr config show
hostmgr sync authorized-keys	hostmgr config sync-authorized-keys

The only thing that could feel odd with this is that set-automatic-login-password / install-helper and sync-authorized-keys are not really related to "the config file", so while the name hostmgr config for that command could still work when interpreted as "configure hostmgr to make it work", this still feels a bit odd

Proposal 2️⃣ : Move everything under hostmgr setup

Old	New
hostmgr set automatic-login-password	hostmgr setup automatic-login-password
hostmgr install hostmgr-helper	hostmgr setup install-helper
hostmgr init	hostmgr setup init-config
hostmgr config	hostmgr setup show-config
hostmgr sync authorized-keys	hostmgr setup sync-authorized-keys

Though it has the opposite odd feeling as 1‍⃣ , where hostmgr setup makes sense for most of the commands but might feel odd to be used for manipulating the config file. Though imho this at least feels a bit less odd than 1‍⃣ ? 🤷

Proposal 3‍⃣ : Split into hostmgr config and hostmgr setup

Old	New
hostmgr set automatic-login-password	hostmgr setup automatic-login-password
hostmgr install hostmgr-helper	hostmgr setup install-helper
hostmgr init	hostmgr config init
hostmgr config	hostmgr config
hostmgr sync authorized-keys	hostmgr setup sync-authorized-keys

Means we'd still keep those commands spread in 2 subcommands instead of one, so they'd still be a bit spread out as they current are, but quite less so at least (i.e. in 2 subcommands rather than 5).
This has the benefit of getting rid of the odd feelings mentioned in 1‍⃣ and 2‍⃣ though with the commands about config file still being separated from the setup ones (but the init of the config file now being properly grouped with the one showing the content)…