[stdlib] Switch to a linear-space variant of Myers diffing (#83212)

This changes the implementation for `Collection.difference(from:)` to
use a linear-space complexity variation of the same Myers algorithm. The
new version is similar in execution time to the existing one, but should
alleviate memory pressure when diffing collections where the number of
differences approaches the size of the collection. While the new
algorithm returns a set of changes that is the same size as the previous
version, the specific changes are not guaranteed to be the same.

rdar://155829876

benchmark/single-source/Diffing.swift

@@ -52,12 +52,12 @@ public let benchmarks = [
   BenchmarkInfo(
     name: "Diffing.Large.Similar",
     runFunction: { diff($0, from: bigUnabridgedLorem, to: bigLoremIpsum) },
-    tags: t,
+    tags: t + [.skip],
     setUpFunction: { blackHole((bigUnabridgedLorem, bigLoremIpsum)) }),
   BenchmarkInfo(
     name: "Diffing.Large.Disparate",
     runFunction: { diff($0, from: bigNumbersAndSymbols, to: bigAlphabets) },
-    tags: t,
+    tags: t + [.skip],
     setUpFunction: { blackHole((bigNumbersAndSymbols, bigAlphabets)) }),
 ]