Enable webpack JS tests for xmodule

[salman2013]

Description:

Karma-webpack tests are disable in edx-platform due to this issue.

We have to re-enable the test-xmodule-webpack which is testing all JS files which was converted from RequireJS to ES6 module.

PR require these test cases to run: #36595

Things to do:

• Figure out how to enable the karma-webpack tests in edx-platform
• Figure out what was the failures and fix them.
• Suggest JS file updates if something miss out during the conversion from RequireJS to ES6

[salman2013]

Here is the PR for this issue: #37351

[kdmccormick]

I updated the title of the ticket to clarify that this fixes test-xmodule-webpack, but test-lms-webpack and test-cms-webpack are still broken.