Revert: revert tsconfig module change for rollup

--- Currently on main, rollup does not inline source files ```js // in packages/babel-plugin-react-forget // $yarn build // output var CompilerError_1 = require("./CompilerError"); Object.defineProperty(exports, "CompilerError", { enumerable: true, get: function () { return CompilerError_1.CompilerError; } }); // ... ``` I debugged a bit but not familiar with node or rollup. - It seems that rollup fails to recognize source file imports with this setting, as resolveId no longer gets called - current `module` option defaults to `ESNext`, which works for some reason. Let's revert for now to unblock syncs. Sanity checked my repro by reinstalling node-modules and cleaning rollup cache.