fix: get module system scoped to context

[pmmmwh]

Fixes #753

[qnighy]

For those who encountered require is not defined issues after upgrading this package above v0.5.11: try upgrading webpack above v5.85.0 as the change introduced in this PR assumes the API introduced in webpack/webpack#17281

(Not a bug report to this plugin itself. Thank you for the great plugin!)

[Jinjiang]

@pmmmwh I hit an error earlier today with webpack@5.84.1. It's always cjs even the file is inside a node module with type: module in its package.json. I guess that's because older version of webpack doesn't have this.environment in the loader context. Now to work with that I have to downgrade to v0.5.9.

Considering the maximum compatibility, shall we check this.environment with an option? Or skip checking it with an option?

Thanks.