Add menu options for not specifying a EAP CA cert and User cert

Add the "Do not validate" and "Do not provide" menu
options for not providing a CA certificate and User certificate
respectively for EAP configurations.

Choosing these options are essentially equivalent to leaving
these fields alone as "(unspecified)" (when that option existed),
but now we require the user to make a conscious choice not to
provide these certificates.

BUG: 26686071
Change-Id: I4b9c07528d6d2ba3eb0787e7cfff69d05dd25679
TEST: Both the added options appear in the relevant menus.
TEST: Choosing both these added options in an EAP-TLS configuration
TEST: allows the configuration to be saved.