break out base_operand infix_notation

[RoDuth]

relates to #278

Example:

from pyparsing import *

binop = one_of("= == != <> < <= > >=").set_name("binary operator")
identifier = Word(alphas, alphanums)
binary_clause = Group(identifier + binop + quoted_string).set_name("binary clause")
on_date_clause = Group(identifier + Keyword("on") + quoted_string).set_name("on date clause")
base_clause = (binary_clause | on_date_clause).set_name("base clause")
query = infix_notation(
    base_clause,
    [
        (Keyword("NOT"), 1, OpAssoc.RIGHT),
        (Keyword("AND"), 2, OpAssoc.LEFT),
        (Keyword("OR"), 2, OpAssoc.LEFT),
    ],
).set_name("clause")
query.create_diagram("test2.html")

In this example even though base_clause has .set_name it is not broken out and hence I get:

where I would expect:

This example is trivial but in my real use case there are 6 parts to base_clause which makes it excessively long.

I can get the expected outcome by wraping in a pointless Group, i.e.

base_clause = Group(binary_clause | on_date_clause).set_parse_action(lambda t: t[0]).set_name("base clause")

Which smells like a dirty hack to me!