refactor(webpack): add ability to get webpack config class

[damianstasik]

Types of changes

• Bug fix (a non-breaking change which fixes an issue)
• New feature (a non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Description

This PR is an improvement of #5366 and adds a new method to WebpackBundler that returns a webpack config class (WebpackClientConfig, WebpackServerConfig or WebpackModernConfig).

I also cleaned up the build method a bit and moved the plugin aliases into WebpackClientConfig and WebpackServerConfig so that each class has all of it's webpack aliases in one place.

Checklist:

• My change requires a change to the documentation.
• I have updated the documentation accordingly. (PR: #)
• I have added tests to cover my changes (if not applicable, please state why)
• All new and existing tests are passing.

[codecov-io]

Codecov Report

Merging #5378 into dev will decrease coverage by 0.03%.
The diff coverage is 95%.

@@            Coverage Diff             @@
##              dev    #5378      +/-   ##
==========================================
- Coverage   96.01%   95.97%   -0.04%     
==========================================
  Files          74       74              
  Lines        2532     2535       +3     
  Branches      641      640       -1     
==========================================
+ Hits         2431     2433       +2     
- Misses         85       86       +1     
  Partials       16       16

Impacted Files	Coverage Δ
packages/webpack/src/config/client.js	98.18% <100%> (+0.18%)	⬆️
packages/webpack/src/config/server.js	100% <100%> (ø)	⬆️
packages/webpack/src/builder.js	93.54% <90%> (-1.46%)	⬇️

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[galvez]

@visualfanatic Please ensure the test suite passes first.

[damianstasik]

@galvez @pi0 fixed, could you take a look?

[clarkdo]

How about returning config object here, then we don't need an extract bind.

Otherwise, if we call config separately, we can leverage Promise.all to enhance config() performance.

[pi0]

@clarkdo Can you please elaborate more about bind?

This function is not async to leverage Promise.all. The runner will be specified based on build type here

[pi0]

@clarkdo Refactor applied. Please review again.

[damianstasik]

@pi0 your change was a surprise, but it was appreciated, thank you.

[clarkdo]

Changed title to refactor for being eligible for v2.5.2

[juliendargelos]

As I proposed here, I think it could be useful for some advanced modules to be able to extend the webpack base config class for independent webpack build based on Nuxt base config. It's just about exposing WebpackBaseConfig (and possibly WebpackClientConfig, WebpackServerConfig and WebpackModernConfig) in index.js:

export { WebpackBundler as BundleBuilder } from './builder'
export { default as WebpackBaseConfig } from './config/base'

[pi0]

There is no guarantee about structure of webpack config classes to be the same across releases. So one can use final result and use/extend it for advanced use cases.