made outputOptions.environment.arrowFunction to false to generate fun…

[cherish2003]

Summary

When libraryTarget is set to module, the externals configuration appends hardcoded arrow functions that cannot be transformed

Fixes (#17861)

Details

Inorder to rectify this issue outputOptions.environment.arrowFunction is made to false in the basicFunction

[linux-foundation-easycla]

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[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)

[alexander-akait]

Fixed here #17919