As prerequisit to implement the switch of subjects to datastreams implement tests for LCSH and RAMEAU identifiers

## Is your feature request related to a problem? Please describe.
In the datastreams version of subjects (https://github.com/inveniosoftware/invenio-vocabularies/issues/322) several identifier schemes should be supported, e.g. gnd, lcsh, rameau and more.

## Describe the solution you'd like
Implement is_lcsh, is_rmeau, normalize_lcsh, normalize_rameau.

## Describe alternatives you've considered
None.

## Additional context
The rameau identifier is an ark implementation (e.g. https://data.bnf.fr/ark:/12148/cb16656930x). It might be sufficient to just check if an id is an ark. So it might be a good idea to first fix #79