Add the automatic storage manager settings.

This provides a toggle for changing if the storage manager
is turned on or off and how many days of data to retain.

It is currently not hooked up to anything currently and only acts as
the view, pending b/28600825.

Bug: 28560570
Change-Id: Iaa2d819f26addab4dc02ced80e9ba79e0fcf0980
6 files changed