Update test framework: fix run_tests.py to support all test files, add auto-import-check for test files

node_modules/import-in-the-middle/test/fixtures/got-alike.mjs

@@ -0,0 +1,11 @@
+// This replicates the way the in-the-wild `got` module does things:
+// https://github.com/sindresorhus/got/blob/3822412/source/index.ts
+
+class got {
+  foo = 'foo'
+}
+
+export default got
+export { got }
+export * from './something.mjs'
+export { default as renamedDefaultExport } from './lib/baz.mjs'