Keep BASIC fixtures within the input line limit

Reflow the approved reference cases, shorten local fixture comments, and split the executable docs line so the 80-byte input buffer can read every source line.

Co-authored-by: andrew <andrew@aklabs.net>

tests/language/arrays_in_parameter_lists.bas

@@ -1,6 +1,6 @@
 10 REM An array reference used as a function argument, and as one of several.
 20 REM An identifier's subscript list used to hang off .right, which is also
-30 REM where an argument list chains its arguments -- so the arity counter walked
+30 REM where arguments chain their arguments -- so the arity counter walked
 40 REM straight into the subscripts and refused the call. TODO.md section 4.
 50 DIM C#(4)
 60 C#(1) = -9