Replaces the existing ESM loader for dealing with external module
imports. This loader was introduced by Aspect for AIO `.mjs` scripts.
The loader will be used as foundation for a more extensive loader
that also properly handles first-party packages.
Additionally another loader is added, all packed as a single
loader because our current NodeJS version only supports a single
loader per node invocation. So we implement chaining ourselves.
The new loader will attempt rewriting `.js` extensions to `.mjs`,
also it will add `.mjs` if not already done. This is necessary
in the transition phase because we don't/cannot use explicit `.mts`
extensions and also we don't specify extensions in imports yet.
Long-term we would likely use `.mts` and explicit import extensions,
but it's not yet clear how we would sync this into g3 too.
PR Close#48521
This is in prearation for having a proper diff when this loader
is adjusted to support more situations than just simple external
node modules. See next commit.
Also the file is formatted to make the diff less verbose later.
The file was never formatted correctly and we don't lint `.mjs` files.
PR Close#48521
