Small updates to OkHttp-Conscrypt interaction

If SNIHostName throws IllegalArgumentException on a hostname, just
ignore it.  Invalid hostnames should just result in no SNI extension.

Add getApplicationProtocol() to DelegatingSSLSocket.  Without it, the
delegating socket used in some tests will report no application
protocol being selected despite one being negotiated, which means the
test will misparse the response since it thinks a different protocol
is being used.

Test: cts -m CtsLibcoreOkHttpTestCases
Bug: 129241395
Bug: 129278464
Change-Id: I750173d8b4a744ac11c0b50f67613fb3a4be3235