Migrated tests to jest

Used jest-codemods to migrate, will have to pass everything by hand before we can merge.

test/sortedIndex/sortedIndex.js

@@ -1,6 +0,0 @@
-const sortedIndex = (arr, n) => {
-const isDescending = arr[0] > arr[arr.length - 1];
-const index = arr.findIndex(el => (isDescending ? n >= el : n <= el));
-return index === -1 ? arr.length : index;
-};
-module.exports = sortedIndex;