Improve the MIME source file

- Add MIME definitions for resources, scenes and scripts
- Remove the "weight" property, which defaults to 50, a much saner value than the previous 100, which was a bit excessive.
- Changes their icon names in order to follow the XDG icon naming conventions.

(cherry picked from commit 876e165a49640a664bd8e60e228140a75c17cf74)

misc/dist/linux/org.godotengine.Godot.xml

@@ -0,0 +1,29 @@
+<?xml version="1.0"?>
+<mime-info xmlns="http://www.freedesktop.org/standards/shared-mime-info">
+  <mime-type type="application/x-godot-project">
+    <comment>Godot Engine project</comment>
+    <icon name="x-godot-project" />
+    <glob pattern="*.godot"/>
+  </mime-type>
+
+  <mime-type type="application/x-godot-resource">
+    <comment>Godot Engine resource</comment>
+    <icon name="x-godot-resource" />
+    <glob pattern="*.res"/>
+    <glob pattern="*.tres"/>
+  </mime-type>
+
+  <mime-type type="application/x-godot-scene">
+    <comment>Godot Engine scene</comment>
+    <icon name="x-godot-scene" />
+    <glob pattern="*.scn"/>
+    <glob pattern="*.tscn"/>
+    <glob pattern="*.escn"/>
+  </mime-type>
+
+  <mime-type type="application/x-gdscript">
+    <comment>GDScript script</comment>
+    <icon name="x-gdscript" />
+    <glob pattern="*.gd"/>
+  </mime-type>
+</mime-info>

misc/dist/linux/x-godot-project.xml

@@ -1,8 +0,0 @@
-<?xml version="1.0"?>
-<mime-info xmlns="http://www.freedesktop.org/standards/shared-mime-info">
-  <mime-type type="application/x-godot-project">
-    <comment>Godot Engine project</comment>
-    <icon name="godot" />
-    <glob pattern="*.godot" weight="100" />
-  </mime-type>
-</mime-info>