Add support for matching explicit intents

This adds a <component-filter> tag for the intent firewall rules,
which adds another top-level filter similar to intent-filter, that
matches intents based on the resolved component they are being sent
to.

Previously, the existing <intent-filter> mechanism did not allow
filtering for explicit intents that had no action/data/etc. The
new <component-filter> functionality can be used for both implicit
and explicit intents.

Change-Id: I6a10e8bfae901931ed2174bca42ea25ac79804d8