Build edx-platform assets without Paver

[kdmccormick]

Background

This issue is at the overlap of two epics:

• Build edx-platform assets without Python #31800
• Process edx-platform assets without Paver #31798

ADR:

• https://github.com/openedx/edx-platform/blob/master/docs/decisions/0017-reimplement-asset-processing.rst#reimplementation-specification

Tasks

• Rewrite build script, including:
  • node_modules copying
  • xmodule_assets invocation
  • Webpack invocation
  • default SCSS compilation
  • theme SCSS compilation
• Run script in CI
• Add & document management command for fetching settings & theme

### PRs
- [ ] https://github.com/openedx/edx-platform/pull/32717
- [ ] https://github.com/openedx/edx-platform/pull/32721
- [ ] https://github.com/openedx/edx-platform/pull/32722
- [ ] https://github.com/openedx/edx-platform/pull/32723
- [ ] https://github.com/openedx/edx-platform/pull/32823
- [ ] Tutor PR

Notes

Blocks:

• Move node_modules outside of edx-platform in Tutor's openedx image openedx-unsupported/wg-developer-experience#150