BoringSSL - Implement bad certificate callback for client SecureSocket connection

[whesse]

Test: standalone/io/https_bad_certificate_test

Implement the onBadCertificate optional argument to SecureSocket.connect() and SecureSocket.secure(), so that a client that gets an unverifiable certificate from the server can call a programmer-provided callback to decide whether to continue the secure connection attempt, or to close the
connection.

[whesse]

Marked this as blocking #23560.

[whesse]

Done.