Fix whitespace sensitive testing for aligned multi-line strings

[crisptrutski]

Unfortunately when you visually align multi-line strings in Clojure, you will accumulate an additional margin due to the current indentation level:

(println "A
            B
          C")

;; A
;;            B
;;          C

Things get worse if you want to define before and after strings with different indentations:

(is (= "A
          X
        C"
       (str/replace "A
                       B
                     C"
                    "B" "X"))) ;; NOPE T_T

Our workaround for this was to collapse contiguous whitespace, but in that case we could have false negatives where we don't detect whitespace being mangled.

This change brings in a method that strips the common indentation from the extra lines, so that the alignment in the actual strings can match how it looks in one's code, emulating the way that multi-line strings are defined in modern languages like Rust.

It also introduces the ws= macro, which strips the common indentation from all string literals within the given form before performing an equality check. This gives great ergonomics for whitespace-sensitive tests. This is a better solution than test-replacements as well, which prevented one from evaluating the inner replacement result form.

[crisptrutski]

Couldn't resist sneaking this in as well 🧼

[tsmacdonald]

I stand by my statements, but am giving you a ✔️ since I trust you to do them without supervision, haha