Port EventRecurrence.parse() from native

This adds a Java-language implementation of EventRecurrence.parse(),
to make it easier to relocate it for the benefit of unbundled
Calendar.

Differences from the native version:

 - enforces that FREQ appears first
 - allows (but ignores) X-* parts
 - improved validation on various values
 - error messages are more specific
 - enforces that only one of UNTIL and COUNT may be present [disabled]
 - allows lower-case property and enumeration values [disabled]

As part of the transition process, both versions of the parser are
called on every request, and the results are compared.  If the results
are different a warning message is logged.

An unnecessary constructor was removed.

This also this moves some EventRecurrence tests out of CalendarProvider,
into coretests, and adds a simple parse test with the examples from
the RFC.

Bug 4575374

Change-Id: If737ed1272fda65c93363d87b2da12b85e644f5b