[Passpoint] OSU system exception when the URL is HTTP

Added checks that the OSU URL is a HTTPS type, and that openConnection
returns an object of HTTPS type before casting it.
Added additional tests.
Add addtional error logs when the OSU cert fails verifications.

Bug: 138444946
Test: atest OsuServerConnectionTest
Test: Verify class cast exception with HTTP URL before the change and
a handled error when the change is applied.
Change-Id: I85b88988f056efd993e19ba157df1d3987b60b27
2 files changed