Allow overwriting media files of dependencies (#10752)

games/devtest/mods/basenodes/textures/dirt_with_grass/info.txt

@@ -1,3 +0,0 @@
-This is for testing loading textures from subfolders.
-If it works correctly, the default_grass_side.png file in this folder is used but
-default_grass.png is not overwritten by the file in this folder.

games/devtest/mods/basenodes/textures/info.txt

@@ -0,0 +1,7 @@
+
+The dirt_with_grass folder is for testing loading textures from subfolders.
+If it works correctly, the default_grass_side.png file in the folder is used but
+default_grass.png is not overwritten by the file in the folder.
+
+default_dirt.png should be overwritten by the default_dirt.png in the unittests
+mod which depends on basenodes.

games/devtest/mods/unittests/mod.conf

@@ -1,2 +1,3 @@
 name = unittests
 description = Adds automated unit tests for the engine
+depends = basenodes