Make consistent module resource locations

[mattt]

The Hub module contains a FallbackConfigs directory containing fallback tokenizer configurations whose contents are bundled as package resources. Whereas ModelsTests and TokenizersTests each contain a Resources directory. This PR renames FallbackConfigs to Resources for consistency. It also moves the Vocabs/bert-vocab.txt file in TokenizerTests to that module's Resources directory.

[FL33TW00D]

Solid clean up!

[pcuenca]

I named it differently to better express intention and because these would ideally be removed at some point in the future. We shouldn't need them, as opposed to resources used elsewhere. It's fine to rename, no need to revert. In fact, I'll check if the reasons still stand or if we can remove.