IKEv2 test with esp=null-none with XFRM/NETKEY

This test first verifies that, by default, west will reject
esp=null-none, but once seriously impaired, it is allowed.

The no-encryption-no-authentication mode is only ever
valid for benchmarking IPsec code

For this test to work both east and west must be impaired as follows:

east:

  allow-null-null[sic]: else the parser will reject null-none

west:

  allow-null-null[sic]: else the parser will reject null-none

  ikev2-include-integ-none: else the code will refuse to include
  'none' in the proposal