Personalize hotseat education

If a user has has 0 apps in the hotseat, jump directly to showing predications.
Otherwise show migration dialog as usual and if user rejects it, show different tips based on the number of available spots.

Bug: 142753423
Test: Manual
Change-Id: Ic5202caf074db2409f6468dd9373875571f3f3c1
(cherry picked from commit aa2aff5a)