Detect if datavault is available/configured and automatically disable WF options requiring datavault

[mbartosch]

Although OpenXPKI can work without a datavault certificate, the standard configuration assumes that it exists. It displays a warning if this is not the case but still offers the WF options (e. g. to use server side key generation) which would fail without a datavault.
In many cases the intended use case does not need a datavault certificate, i. e. if only EE CSRs are processed and server side key generation is not used.

Suggestion for improvement:
Detect if a datavault token is configured. If this is not the case, disable all WF paths which require a functional datavault.