Instead of using @hasDecl, use a performAction-stype API. The C
interface for interfacing with macOS (or any other apprt where Ghostty
is embedded) is unfinished.
This adds the `-e` flag to the `+new-window` CLI action. This allows a
command to be passed from the CLI to the running instance of Ghostty.
Nothing is done with that command besides logging its presence.
- Add a `GHOSTTY_CLASS` environment variables to any command executed by
Ghostty to make discovering the correct application ID easier.
- Add a flag to force the relelase application ID.
- Ensure that CLI flags to `+new-window` are mutually exclusive.
- Fix documentation about D-Bus activation requirements.
This will (on GTK) use a D-Bus method call to tell a running
Ghostty instance to open a new window. If D-Bus activation is
configured properly, Ghostty does not need to be running first.
This could be extended to other platforms, e.g. AppleScript on macOS
eventually.
When Ghostty develops a native API, that could be used instead to create
a new window.
