Put the machine into the limbo state when it join Omni for the first time

[Unix4ever]

Change the process of the machine join. The process will look like this:

0. Store the unique token in the link resources.
1. Talos does the request to the siderolink API.
2. Omni takes the decision what to do with the machine:
   1. if the machine has no unique token, put the machine into the limbo state unconditionally.
   2. If the machine has unique token and it matches with what is stored in the link, let the machine join.
   3. if the machine has the unique token and it doesn't match, reject the machine.
3. For the machines in the limbo state:
   1. check the policy for the machine join (can depend on the token type) and let the machine in or leave it in the limbo state.
   2. user can accept the machine which is in the limbo state, Omni will let it fully join.
   3. if there's a link with non-empty unique token and the same UUID, Omni should generate a unique UUID for the machine in the limbo state.
4. For each machine in the limbo state which was accepted, generate a unique token.
5. For each machine with the unique token, create a link.

Migration should be handled: if the link exists and there's no unique token, let the machine in without putting it into a limbo state.

We can use the Wireguard address of the connected machine as the ID for the machines in the limbo state.