Test line range handling

[jackfirth]

The cause of #298 was improper handling of line range filtering in source-analyze. To avoid similar issues, I ought to augment #lang resyntax/testing/refactoring-test with the ability to specify that only a subset of lines in the test case should be analyzed. Something like this:

test: "define let should be refactored to double define without analyzing other lines"
lines: 4-6
--------------------
(define (foo)
  (define (bar)
    (displayln "bar"))
  (define y
    (let ([x 1])
      (* x 2))
  (define (baz)
    (displayln "baz")))
--------------------
--------------------
(define (foo)
  (define (bar)
    (displayln "bar"))
  (define x 1)
  (define y (* x 2))
  (define (baz)
    (displayln "baz")))
--------------------