Fix missing document icons on macOS 10.4 and earlier

Re-adds a legacy document icon for macOS 10.14 Mojave that is
consistent with the system generated document icon on macOS 11
Big Sur. It uses the old-style document sheet icon, but includes the
file extension underneath the Blender icon (unlike the previous
legacy document icon that was removed in D10267).

Adds the missing description for the exported type identifier.
Finder now correctly displays “Blender File” instead of “data”
for Blender files.

Differential Revision: https://developer.blender.org/D10746

release/darwin/Blender.app/Contents/Info.plist

@@ -11,6 +11,8 @@
 			<array>
 				<string>blend</string>
 			</array>
+			<key>CFBundleTypeIconFile</key>
+			<string>Blender_Legacy_Document_Icon.icns</string>
 			<key>CFBundleTypeName</key>
 			<string>Blender File</string>
 			<key>CFBundleTypeOSTypes</key>
@@ -62,6 +64,8 @@
 			</array>
 			<key>UTTypeIdentifier</key>
 			<string>org.blenderfoundation.blender.file</string>
+			<key>UTTypeDescription</key>
+			<string>Blender File</string>
 			<key>UTTypeIcons</key>
 			<dict>
 				<key>UTTypeIconName</key>