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/flowcontrol/nestedforloopwaitingforcommand.bas

@@ -1,6 +1,6 @@
 10 REM This shows the waitingForCommand utility in the BasicEnvironment
 11 REM when we have a nested for loop. The inner loop SHOULD execute, but
-12 REM the outer loop should NOT execute. Therefore, neither loop should execute.
+12 REM the outer loop should NOT execute. Neither loop should execute.
 20 FOR I# = 1 TO 0
 25 FOR J# = 2 TO 4
 30 PRINT "waitingForCommand FAILS if this is seen"
@@ -8,4 +8,4 @@
 35 NEXT J#
 40 NEXT I#
 50 PRINT "SUCCESS"
-80 QUIT
+80 QUIT