landing page update

[DAC098]

The landing page, when not logged in, should look like the following:

• The request a free teacher account link should navigate to https://forms.gle/TFJP5Uc746LUs3Vz8 in a new page (i.e. target="_blank")
• The All Languages dropdown should default to the all languages option, but also allow the selection of any of the languages available among open-enrollment courses. Selecting another language should update the list of open-enrollment courses that match that language.
• All open-enrollment courses should be listed, sorted in the order of most-enrolled students to least.
• Each course listed should display the course name, language, and a list of the module names (in order as they're listed in the course).

Clicking the join button should lead users to log in and, upon success, bring them to the course page with the student course view (showing the current--first--module).

[kbuffardi]

Figma design: https://www.figma.com/design/91OqiYNXxawxbxm7FkhjuD/Student-view?node-id=446-77&m=dev

[kbuffardi]

Also, the Join open-enrollment courses section should be added to the home page when the user is logged in, as well. It should be shown below the Attending courses section.