make sure that the callback function in module.hot.accept is parsed

[sokra]

fixes #11057

What kind of change does this PR introduce?
bugfix

Did you add tests for your changes?
yes

Does this PR introduce a breaking change?
no

What needs to be documented once your changes are merged?
nothing

[webpack-bot]

For maintainers only:

• This needs to be documented (issue in webpack/webpack.js.org will be filed when merged)
• This needs to be backported to webpack 4 (issue will be created when merged)

[webpack-bot]

Thank you for your pull request! The most important CI builds succeeded, we’ll review the pull request soon.

[pmmmwh]

Should this also apply to module.hot.dispose, module.hot.addDisposeHandler and module.hot.removeDisposeHandler 👀 ?

This fix will remove some hacks I needed to get React Fast Refresh working for webpack 5 😍