Open URIs from the CLI, support for the zed:// URI scheme on Linux (#14104)

Allows Zed to open custom `zed://` links (redirects from
https://zed.dev/channels) on Linux used XDG MIME types.

This PR also allows the CLI to be able to open Zed (`zed://`) URIs
directly instead of executing the main executable in
`/usr/libexec/zed-editor`.


Release Notes:

- Linux: Allow `zed.dev/channel` (`zed://`) URIs to open on Linux
- CLI: Ability to open URIs from the command line

---------

Co-authored-by: Conrad Irwin <conrad.irwin@gmail.com>

crates/zed/resources/zed.desktop.in

@@ -4,13 +4,13 @@ Type=Application
 Name=$APP_NAME
 GenericName=Text Editor
 Comment=A high-performance, multiplayer code editor.
-TryExec=$APP_CLI
+TryExec=$APP
 StartupNotify=$DO_STARTUP_NOTIFY
 Exec=$APP_CLI $APP_ARGS
 Icon=$APP_ICON
 Categories=Utility;TextEditor;Development;IDE;
 Keywords=zed;
-MimeType=text/plain;inode/directory;
+MimeType=text/plain;inode/directory;x-scheme-handler/zed;
 Actions=NewWorkspace;
 
 [Desktop Action NewWorkspace]