suggestion: make Protocols an ResearchProduct

[lzehl]

This would give us better alignment with https://www.protocols.io

For EBRAINS: this could raise the incentive to publicly register Protocols. protocols.io gives a good example on how a protocol should be written. Potentially we could then even provide DOIs from EBRAINS for protocols as well (@olinux ?). It is also an option to integrate public protocols from protocols.io (the API seems to be be well documented so mapping to openMINDS should be possible)