Change the type of Server Action

## Affects:
Server Actions

## Need for this:
Links the Change the type of server action

## Hetzner API documentation
https://docs.hetzner.cloud/#server-actions-change-the-type-of-a-server

## Tasks
- [ ] Implement method on Server class
- [ ] Add new Action enum
- [ ] Implement change in ServerChangeListener
- [ ] Implement change in ServerService
- [ ] Add testing