Add terms for maintainer and provider in controlled vocabulary for roles

[mhucka]

In the controlled vocabulary for roles at https://github.com/caltechlibrary/caltechdata_api/blob/main/caltechdata_api/vocabularies/roles.yaml, there currently are no roles matching the CodeMeta fields maintainer and provider. A bunch of Codemeta fields like contact do have suitable role terms, but not those two. To improve the mapping from CodeMeta to data.caltech.edu's InvenioRDM records, it would be useful to add maintainer and provider to the "roles" CV.