Update copy for battery estimate related features

Many features are using the enhanced estimates but the copy for them
has gotten out of sync. This CL moves shared strings between Settings
and SysUI to SettingsLib and also updates features that use the
strings to have consistent behavior/text.

Test: Robotests
Bug: 65656091
Bug: 66909350
Bug: 67469159
Change-Id: Ie5ef1ed65429ca9805cff374f1439e5d61eb6591