check parameter= is rejected when {left,right}prefix is required

It was being interpreted as rightparameter=.  For instance updown= was
silently interpreted to rightupdown=.

In 5.3 a warning was added.

In 5.4 the warning was changed to an error (i.e., the connection add
is rejected).

If code ever uses kv_both on a parameter.  For instance:

-  KWS("updown", kv_leftright, KWS_UPDOWN),
+  KWS("updown", kv_both|kv_leftright, KWS_UPDOWN),

so that "updown=..." implies both {left,right}updown=), then this test
should be updated to also test that case.  For now it has stubs.
