Fix support of resources localized with region code

[dr1rrb]

• Fix resources generation support for resources localized with region code
• Fix fallback mechanism of the Resource loader

GitHub Issue (If applicable): #493

PR Type

What kind of change does this PR introduce?

• Bugfix

What is the current behavior?

1. If a resource file is added with a region code, the resource generator will either ignore it or place it in an invalid location for the Android localization file structure
2. When a resource is missing for the current UI culture, the ResourceLoader will not fallback properly on the DefaultLanguage (if the current UI culture is fr-FR and the default language is en-US, it tries only fr-FR and fr)

What is the new behavior?

1. File structure is now valid so Android is able to load resources by itself
2. If the current UI culture is fr-FR and the default language is en-US, ResourceLoader will now try (in that order) fr-FR , fr, en-US and en

PR Checklist

Please check if your PR fulfills the following requirements:

• Tested code with current supported SDKs
• Docs have been added/updated which fit documentation template. (for bug fixes / features)
• Unit Tests and/or UI Tests for the changes have been added (for bug fixes / features) (if applicable)
• Contains NO breaking changes
• Updated the Release Notes
• Associated with an issue (GitHub or internal)

Internal Issue (If applicable):
https://nventive.visualstudio.com/Umbrella/_workitems/edit/144268