Merge the "Course Info" and "Prerequisite Not Met" Popovers

[Awesome-E]

There are currently two popovers inside Course.tsx: one with overlay={CoursePopover} and one with overlay={WarningPopover}.

These two should be combined into one component and be extracted into its own component file.

Instead of having the info circle and the warning icon, we should prefer the warning icon when prerequisites are not met, and use the info circle otherwise.

Here are the two popups this issue aims to combine:

Here's an example design of a roadmap quarter after this issue:

(you do not have to worry about changing/hiding course titles as that's not in scope of this issue)

Here's an example of what that merged popup could look like when you hover the info circle or warning icon: