Implement new API for ACS/SLO data in metadata

[waterkip]

Supports more control over which indexes go where for AssertionConsumerServices
and you can change which one the default is as well. The old constuctor syntax
is still supported but translated to this new setup.

my $sp = Net::SAML2::SP->new(
      single_logout_service => [
          {
              Binding => BINDING_HTTP_REDIRECT,
              Location => 'https://foo.nl',
          },
      ],
      AssertionConsumerService => [
          # order decides index?
          {
              Binding => BINDING_HTTP_ARTIFACT,
              Location => ...,
              # index 1
          },
          {
              Binding => BINDING_HTTP_POST,
              Location => ...,
              # index 2
              isDefault => 1,
          }
      ],
      ...,
);

Closes: #46

Signed-off-by: Wesley Schwengle wesley@opndev.io