inspector: Add .ui.h files to git

Tools like damn-lies rely on being able to generate .pot files
from pristine checkouts, so everything that goes into the .pot
file has to be in git. This is not ideal, but we already do
the same for other .ui.h files in GTK+.

gtk/inspector/window.ui.h

@@ -0,0 +1,20 @@
+N_("Send Widget to Shell");
+N_("Select an Object");
+N_("Miscellaneous");
+N_("Properties");
+N_("Signals");
+N_("Hierarchy");
+N_("Child Properties");
+N_("CSS Classes");
+N_("Style Properties");
+N_("Custom CSS");
+N_("Size Groups");
+N_("Data");
+N_("Actions");
+N_("Menu");
+N_("Gestures");
+N_("Objects");
+N_("Resources");
+N_("Custom CSS");
+N_("Visual");
+N_("General");