Summary

Adds a webpack 5 compatible version of @rushstack/localization-plugin, intended to be published as major version 5 of the same name.
Depends on #3455 for necessary changes to @rushstack/localization-utilities.

Details

The interface for the webpack 5 plugin is a bit more generic and less opinionated than the webpack 4 version, and requires developers to install the loaders manually (as they would for, e.g. mini-css-extract-plugin). The loaders support json or javascript/esm output for flexibility.

The plugin adds support for the [locale] token in the output.chunkFilename and output.filename webpack configuration properties.

How it was tested

Unit test coverage of:

• No localized strings files -> all chunks have locale none
• No async chunks, but with localized strings -> localized entry chunks
• Localized files in async chunks, no dynamic locale expression -> localized async chunks + localized runtimes
• Localized files in async chunks, dynamic locale expression -> localized async chunk + generic runtime
• Changing translations changes chunk hash
• Localized stats files