feat(transformer): run exec.js from babel tests

[Boshen]

Babel has execution tests such as https://github.com/babel/babel/blob/main/packages/babel-plugin-transform-exponentiation-operator/test/fixtures/exponentiation-operator/comprehensive/exec.js

We need a test runner which reads, transforms and then runs these files to make sure our transformation is correct. The test runner should invoke either node.js (or bun for performance).