This removes `launched-from` entirely and moves our `gtk-single-instance`
detection logic to assume true unless we detect CLI instead of assume
false unless we detect desktop/dbus/systemd.
The "assume true" scenario for single instance is desirable because
detecting a CLI instance is much more reliable.
Removing `launched-from` fixes an issue where we had a
difficult-to-understand relationship between `launched-from`,
`gtk-single-instance`, and `initial-window`. Now, only
`gtk-single-instance` has some hueristic logic. And `initial-window`
ALWAYS sends a GTK activation signal regardless of single instance or
not.
As a result, we need to be explicit in our systemd, dbus, desktop files
about what we want Ghostty to do, but everything works as you'd mostly
expect.
Now, if you put plain old `ghostty` in your terminal, you get a new
Ghostty instance. If you put it anywhere else, you get a GTK single
instance activation call (either creates a first instance or opens a new
window in the existing instance). Works for launchers and so on.
Fixes#7673
This adds `Ctrl+Alt+T` as a KDE shortcut to the desktop file. If Konsole
is installed (or any other prorgam that has the same shortcut) the user
will need to go into the KDE system settings and manually reassign the
`Ctrl+Alt+T` shortcut to Ghostty.
If Ghostty is the only terminal installed that claims that shortcut KDE
_should_ automatically enable the shortcut (but YMMV).
Non-KDE systems will ignore this setting and if the user desires a
global shortcut to open a Ghostty window it will need to be accomplished
in other ways.
