Show where each item starts in the inspiration and sync lists

Items in the inspiration list and the sync result columns now each have
their own background box, alternating between two shades, with a small
gap between them. When a long name wraps over several lines it is
still clear which lines belong together. The sync columns keep their
alternating white and orange text.

tests/unit/test_list_row.gd.uid

@@ -0,0 +1 @@
+uid://bouligcywd5se