Add Unity's Addressables and Android's temp files. (#3311)

* Added Addressables.

Prevent automatically generated addressable files to end up in Git.

* Update .gitignore to exclude packed Addressables and Android auto-generated files.

Unity.gitignore

@@ -62,3 +62,9 @@ sysinfo.txt
 # Crashlytics generated file
 crashlytics-build.properties
 
+# Packed Addressables
+/[Aa]ssets/[Aa]ddressable[Aa]ssets[Dd]ata/*/*.bin*
+
+# Temporary auto-generated Android Assets
+/[Aa]ssets/[Ss]treamingAssets/aa.meta
+/[Aa]ssets/[Ss]treamingAssets/aa/*