Tutor Indigo Theme Updates

[hinakhadim]

No description provided.

[regisb]

Thanks for opening this preliminary PR Hina. I see that we are overriding many html templates. If we do not take some precautions it's going to be extremely difficult to upgrade those in the future. Can we keep our html changes to a minimum? And where changes are needed, clearly label them with an HTML comment.

[hinakhadim]

Regis, We've removed the static files which we haven't overridden. Also, Not a lot of changes we've made but comments has been added by Tanveer where he made changes in the html files.
I've also added the ENV_PATCHES for the learning-mfe. This will install the header, footer and brand-openedx in learning-mfe image.

[regisb]

This is awesome work. I'm eager to see this live.

landing page

When unauthenticated, the "explore courses" menu in the top left corner looks off:

favicon

I think we should not use the "" logo for the favicon: it's not neutral enough. Instead, we should use the blue "<>" logo:

course about page

In the course "about" page, when I hover on the social sharing links, the "Share with friends and family" modal looks off. The background should not be black, the font should not be serif and not italic:

[regisb]

Closed in favour of #54