android: renamed strings.xml to strings_unlocalized.xml

Summary: 9079bed wasn't enough to blacklist the strings.xml files from FB infra. So this is a better workaround. According to https://developer.android.com/guide/topics/resources/string-resource the .xml file names doesn't really matter, so this shouldn't break the ability to get the string resource in code, like `R.strings.foo`.

Reviewed By: yungsters

Differential Revision: D15103303

fbshipit-source-id: 6d5174a8dc9598930670d35434e1494f9eaea059

Author: fkgozali