(This is a merge of http://go/wvgerrit/71883)
This moves all the SSL code to privacy_crypto so we can use the
iOS-specific versions and not use any BoringSSL. The iOS version
doesn't support OEM certificates.
Note that the tests still use BoringSSL.
Bug: 126559819
Test: build_and_run_all_unit_tests.sh
Change-Id: Ib0fad5d95b283b6cd6e02d8a08bcf248c5900bc4