feat: adds support for loading external theme CSS for MFEs

[dcoa]

Description:

This PR updates the original one https://github.com/openedx/frontend-platform/pull/440 closer to the master branch and adds some extra tests.

Please read the original PR for additional context.

[!WARNING] The dist folder is included in the PR for testing purposes and will be removed before the merge.

Merge checklist:

• [x] Consider running your code modifications in the included example app within frontend-platform. This can be done by running npm start and opening http://localhost:8080.
• [x] Consider testing your code modifications in another local micro-frontend using local aliases configured via the module.config.js file in frontend-build.
• [ ] Verify your commit title/body conforms to the conventional commits format (e.g., fix, feat) and is appropriate for your code change. Consider whether your code is a breaking change, and modify your commit accordingly.

Post merge:

• [ ] After the build finishes for the merged commit, verify the new release has been pushed to NPM.

[openedx-webhooks]

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[codecov[bot]]

Codecov Report

Attention: Patch coverage is 83.90093% with 52 lines in your changes missing coverage. Please review.

Project coverage is 83.64%. Comparing base (bc9c233) to head (837858e).

Files	Patch %	Lines
src/react/hooks/paragon/useParagonThemeVariants.js	81.57%	19 Missing and 2 partials :warning:
src/react/hooks/paragon/useParagonThemeCore.js	80.95%	15 Missing and 1 partial :warning:
src/react/hooks/paragon/utils.js	78.78%	7 Missing :warning:
src/react/hooks/paragon/useParagonTheme.js	84.37%	4 Missing and 1 partial :warning:
src/react/reducers.js	84.61%	2 Missing :warning:
src/react/hooks/paragon/useParagonThemeUrls.js	96.77%	1 Missing :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #689 +/- ## ========================================== + Coverage 83.41% 83.64% +0.23% ========================================== Files 40 48 +8 Lines 1073 1388 +315 Branches 197 290 +93 ========================================== + Hits 895 1161 +266 - Misses 166 211 +45 - Partials 12 16 +4 ```

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[PKulkoRaccoonGang]

@dcoa I'm getting an error during build related to the env.config.js file

SyntaxError: Unexpected token 'export'

I tried to solve it by changing the export to module.exports = { config }; I succeeded, but the content of the example application is not rendered on http://localhost:8080.

Have you encountered such a problem?

[dcoa]

@PKulkoRaccoonGang this is related to frontend-build changes, I'm checking right now

This line is making that the app is not rendering in frontend-platform https://github.com/openedx/frontend-build/pull/546/files#diff-22e13ddf245ea4fa81ca4d686dddf46fa9cbf70fbbff99991cccbf0c8ff82316R175

If you remove it, you will be able to see the app.

Update

I made an update to webpack dev config for example app and is working now.

[arbrandes]

@davidjoy, this is a doozy to keep an eye on.

[davidjoy]

Sure is. It looks like it was temporary, but just to explicitly note it: the dist folder has been checked in in this PR. We need to remember to remove that before merging.