ZygoteInit: install AndroidKeyStoreProvider in the Zygote

Instead of in activity thread. That way, we can warm up (ie,
precompute cached values) this provider and AndroidBCWorkaroundProvider
(which are installed together) so that the computation doesn't
happen in the app. As a result, the time spent in the first call to
SSLSocketFactory.getDefault() decreases by ~5ms in angler userdebug.
Measured with an app calling SSLSocketFactory.getDefault in onCreate
and timed it with System.currentTimeMillis() .

Bug: 28545496

Change-Id: I73284eccdf6d51dbf55206335d759ccf795c5f41