refactor(FAQ): Extract common code to parent

[hirokiterashima]

Changes

• Extract common code in TeacherFaqComponent and StudentFaqComponent to new FaqComponent (in new help/faq directory)
• Move common styles to faq.component.scss
• Clean up FaqComponent code a bit using pipe() and filter()

Test

• Teacher and Student FAQ pages work as before
  • links take you to the right place
  • styles look the same as before

[breity]

Looks good. 👍

I updated a bit to remove unnecessary CSS and also converted the table of contents links to use native Angular anchor scrolling. (I also fixed anchor scrolling in the main app, as it was broken.)

I modified the GettingStarted component to extend FaqComponent as well, since it uses the same functionality as the student and teacher FAQ components.

[hirokiterashima]

Thanks. The new styles and anchors look good.

It feels a bit strange that GettingStartedComponent extends the FaqComponent. It may make sense in the future to make a HelpPageComponent that is extended by [Student/Teacher]FaqComponent and GettingStartedComponent.