Untuck tests out of __tests__ directories, colocate with program files

src/utils/input.test.ts

@@ -0,0 +1,7 @@
+import { normalizeUsername } from './input';
+
+test('normalizeUsername', () => {
+  expect(normalizeUsername('@alex')).toBe('alex');
+  expect(normalizeUsername('alex@alexgleason.me')).toBe('alex@alexgleason.me');
+  expect(normalizeUsername('@alex@gleasonator.com')).toBe('alex@gleasonator.com');
+});