commando: integer command parameters can be compared with < and >.

Previously any attempt would result in "is not an integer field"; we
now recognize valid JSON integers as integer fields.

Changelog-Fixed: Plugins: `commando` runes can now compare integer parameters using '<' and '>' as expected.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

tests/test_plugin.py

@@ -2991,7 +2991,6 @@ def test_commando_listrunes(node_factory):
     assert not_our_rune['our_rune'] is False
 
 
-@pytest.mark.xfail(strict=True)
 def test_commando_rune_pay_amount(node_factory):
     l1, l2 = node_factory.line_graph(2)