hst/dbus: move dbus config struct

This allows holding a xdg-dbus-proxy configuration without importing system/dbus.

It also makes more sense in the project structure since the config struct is part of the hst API however the rest of the implementation is not.

Signed-off-by: Ophestra <cat@gensokyo.uk>

system/dbus/dbus_test.go

@@ -22,7 +22,7 @@ func TestFinalise(t *testing.T) {
 			err, syscall.EBADE)
 	}
 
-	for id, tc := range testCasePairs() {
+	for id, tc := range testCasePairs {
 		t.Run("create final for "+id, func(t *testing.T) {
 			var wt io.WriterTo
 			if v, err := dbus.Finalise(tc[0].bus, tc[1].bus, tc[0].c, tc[1].c); (errors.Is(err, syscall.EINVAL)) != tc[0].wantErr {
@@ -105,7 +105,7 @@ func testProxyFinaliseStartWaitCloseString(t *testing.T, useSandbox bool) {
 		}
 	})
 
-	for id, tc := range testCasePairs() {
+	for id, tc := range testCasePairs {
 		// this test does not test errors
 		if tc[0].wantErr {
 			continue