2. Update COMPREHNSIVE_THEME_DIR to COMPREHENSIVE_THEME_DIRS
3. Update paver commands to support multi theme dirs
4. Updating template loaders
5. Add ENABLE_COMPREHENSIVE_THEMING flag to enable or disable theming via settings
6. Update tests
7. Add backward compatibility for COMPREHEHNSIVE_THEME_DIR

Don't use symlinks to include node_modules

TNL-4335

TNL-4335

Resolves conflicts between reverts of pattern library test pages and multi-site comprehensive theming, and the re-introduction of pattern library test pages. Fixes a pipeline rendering test which relied on other tests updating assets. The test now ensures that static assets are available before running.

FEDX-93

These are developer only pages, so can not be seen in production
environment. On devstack, you can access these pages in LMS and
Studio at:

    /template/ux/reference/pattern-library-test.html

This is the second attempt to enable the Pattern Library. The
first attempt broke Django Templates and didn't work correctly
with right-to-left styling.

Instead of attempting to derive the module portion of a RequireJS
override strictly from the path to the JS file, we now use a dictionary
where the module name must be explicitly specified.  This allows us to
compensate for files which do not follow a naming scheme that is
compatible with RequireJS without having to normalize all files.  This
is extremely important when using third-party dependencies.

TNL-3954

This reverts commit b8184d18.

[second attempt which addresses bug building Studio]

This reverts commit 1d6fceda.

Respond to review comments:

- Rename build and config files for consistency between lms/studio.
- Fix merge conflicts with lms require config.
- Devstack uses optimized pipeline to skip require JS optimizer step
- Add tests for render_require_js_path_overrides