Allow Zed to run under multiple user accounts simultaneously (#14143)

Closes #4607

This is an attempt to enable Zed to run under multiple user accounts on
the same Mac, because it's a blocker to me really giving Zed a fair shot
at being my primary editor.

According to some helpful info from @ForLoveOfCats in #4607 the main
reason why this doesn't work is because Zed is using a Unix socket or
maybe a TCP socket with a hard-coded path and/or port. To me it looks
like it's a TCP socket so I tried changing that code in here, but I'm
stuck at trying to test it out because running `target/debug/zed` or
`target/release/zed` seems to behave differently than running an actual
app bundle. I had no luck copying the binary over to
/Applications/Zed.app/Contents/MacOS/zed because it can't find
WebRTC.framework which resides at a different relative path in the app
bundle.

If this seems like a desirable change to the core team then I'm looking
for some guidance on how to build an app bundle or otherwise test out
this change, or a nudge in the correct direction if I'm way off base
with my current approach.

Release Notes:

- Added multiuser support for up to 100 users on the same machine.

---------

Co-authored-by: Mikayla <mikayla@zed.dev>

crates/zed/Cargo.toml

@@ -113,6 +113,7 @@ vim.workspace = true
 welcome.workspace = true
 workspace.workspace = true
 zed_actions.workspace = true
+sysinfo.workspace = true
 
 [target.'cfg(target_os = "windows")'.dependencies]
 windows.workspace = true