separate spacetime init/dev client and server templates

[xDovos]

currently spacetime init/dev templates have the client and server together in the same template folder.
this is so that the client code is compatible with the server code but it also means that it is not possible to select different languages between the client and server. if all templates that contain the same code are named the same (except the language), then it wouldn't matter if the client and server templates are selected in two steps.

so to have for example a rust server and TS client, it would require to make a rust server only, and init another TS server + client and then delete the new TS server and replace it with the earlier created rust server.

it is also not possible to make just a client or just a server once the command is run. the spacetime init has a --server-only flag but it can only be used with the start of the command and not as option later. there is no flag for just a client.

there is also a flag for the server language but not for the client language, so it is not possible to use init without going through the dialogue if you want to have a client too.

[xDovos]

It would also be nice to separate out the AI rules and related files into its own step and have the init choose which AI it wants to have or none at all. It doesn't look good when you get blanked spammed with AI rules and folders that you don't need.