Train selected course

[kylexrich]

Will demo all of these features in our next standup. Got way too carried away. But everything seems to be working nicely.

Wont even let me link all of the issues haha. Here is all of them:

• https://github.com/kylexrich/coursegpt/issues/61
• https://github.com/kylexrich/coursegpt/issues/74
• https://github.com/kylexrich/coursegpt/issues/55
• https://github.com/kylexrich/coursegpt/issues/72
• https://github.com/kylexrich/coursegpt/issues/102
• https://github.com/kylexrich/coursegpt/issues/103
• https://github.com/kylexrich/coursegpt/issues/94
• https://github.com/kylexrich/coursegpt/issues/95
• https://github.com/kylexrich/coursegpt/issues/98
• https://github.com/kylexrich/coursegpt/issues/99
• https://github.com/kylexrich/coursegpt/issues/97
• https://github.com/kylexrich/coursegpt/issues/101