remoting (#9680)

This PR provides some of the plumbing needed for a "remote" zed
instance.

The way this will work is:
* From zed on your laptop you'll be able to manage a set of dev servers,
each of which is identified by a token.
* You'll run `zed --dev-server-token XXXX` to boot a remotable dev
server.
* From the zed on your laptop you'll be able to open directories and
work on the projects on the remote server (exactly like collaboration
works today).

For now all this PR does is provide the ability for a zed instance to
sign in
using a "dev server token". The next steps will be:
* Adding support to the collaboration protocol to instruct a dev server
to "open" a directory and share it into a channel.
* Adding UI to manage these servers and tokens (manually for now)

Related #5347

Release Notes:

- N/A

---------

Co-authored-by: Nathan <nathan@zed.dev>

crates/collab/src/db/tables.rs

@@ -10,6 +10,7 @@ pub mod channel_message;
 pub mod channel_message_mention;
 pub mod contact;
 pub mod contributor;
+pub mod dev_server;
 pub mod extension;
 pub mod extension_version;
 pub mod feature_flag;