API council requested tweaks to SubscriptionPlan.

Return new shiny Range<> object instead of Pair<>.  Tell developers
what permission to check on refresh broadcast.  Describe what
exceptions might be thrown, and that an empty list is okay.

Allow creation of plans with richer Period object, instead of forcing
them into rigid week or day options.

Protect SubscriptionPlan broadcast.

Test: atest android.util.RecurrenceRuleTest
Test: atest com.android.server.NetworkPolicyManagerServiceTest
Bug: 74945820
Change-Id: I7e555798e0cfaa214ca93d9df627c6443fc5d986