Description of change
Add charms to the model cache, including adding CharmInfo to the multiwatcher, and ModelUUID to the charmDoc in state to facilitate the change to model cache. Add Principal element to UnitInfo in the model cache. Update core/lxdprofile to allow for LXDProfiles in CharmInfo.
QA steps
It's not used yet, so at best will cause no problems.
该提问来源于开源项目：juju/juju
