Migrate to webpack 5, use caching on builds.

Summary

Building assets in pipelines is taking a long time.

Webpack 5 should support caching to the filesystem out of the box.

The cache can be published as an artifact, and reused across builds.

records will allow consistent hash names on chunks/modules so the client would only need to re-download assets that change. (better performance in production likely)

the clean option is supported in webpack 5, and will allow builds to clean up old/unused files.

gotchas

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• new vue-loader versions are for vue3 - "vue-loader": "^15.0.0" is for webpack 5 with vue2
• Dynamic imports don't work when exports specified in package.json