feat: expose webpack.target as rawTarget

[bpinto]

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Please check if the PR fulfills these requirements

• Tests for the changes have been added (for bug fixes / features)
• Docs have been added / updated (for bug fixes / features)

What kind of change does this PR introduce? (Bug fix, feature, docs update, ...)

• Bugfix
• Feature
• Code style update (formatting, local variables)
• Refactoring (no functional changes, no api changes)
• Build related changes
• CI related changes
• Other... Please describe:

What is the current behavior? (You can also link to an open issue here)

Currently the target exposed via caller.target is the normalized target.

What is the new behavior?

This change adds a new property called rawTarget that exposes the original target as set on the webpack configuration.

Does this PR introduce a breaking change?

• Yes
• No

If this PR contains a breaking change, please describe the following...

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• Migration path for existing applications:
• Github Issue(s) this is regarding:

Other information:

In the future, I think browserlistEnv option could be automatically set when the webpack's target option is set using browserslist:${env}. I believe that would make the webpack / babel / browserslist integration easier.

I'm afraid that would be a breaking change, and since there are, based on the documentation, future breaking changes it might make sense to wait for that to introduce this automatic browserlistEnv setting.

[bpinto]

I have not updated any documentation nor included any test yet. But I'd like some guidance on how to do both if this change is considered interesting.

[bpinto]

I'm not used to working on packages that require being pre-built before they can be used in a project, so if possible could you tell me how can I test this change on my project? I tried adding it to package.json using the git URL but that is not enough. Meanwhile, I have copied these changes over to the installed package (on node_modules) in order to try this out.

[bpinto]

Maybe I should add this below the target property below?

[bpinto]

@nicolo-ribaudo do you think this is worth adding? See #826 (comment) for context. I would like to be able to use different browserslist targets and for that I need to pass the raw target to @babel/preset-env.