Construct ChangeDatas with ChangeControls in REST handlers

This is strictly less work than constructing them with Changes, as
ChangeControls never need to be lazily loaded.

Unfortunately there are still many more callers where it was not
obvious whether a ChangeControl could be passed in, so I just got the
easy ones.

Change-Id: Ic1c8c2f6aedb25df6c64595f3aecc0e9d2c96817
3 files changed