Gradually increase the level of authentication on failed GATT operations.

When lower layer returns insufficient authentication or insufficient
encryption on various GATT operations, gradually retry with increased
authentication level first to AUTHENTICATION_NO_MITM, then
AUTHENTICATION_MITM.

Test: ported from internal branch.

Change-Id: I6bcc4198ca493b7900ddd166a81d30cde896fa86
1 file changed