Support caveats on endowment permissions

[FrederikBolding]

This PR adds caveat support for endowment permissions, see the linked issue for why this is needed now.

WIP

Description

Itemize the changes you have made into the categories below

• CHANGED:
  • Allowed endowment permissions to specify caveats

Checklist

• [ ] Tests are included if applicable
• [ ] Any added code is fully documented

Issue

Resolves #877