Create the professor-course/sections/trends route and move all trends-related route to one controller

[mikehquan19]

We've got 2 routes course/sections/trends and professor/sections/trends, which allowed for fast querying of sections from the aggregated collections trends_course_sections & trends_prof_sections.

Add another route combined/sections/trends which can query sections (with embedded course and professor objects) from collection trends_course_and_prof_sections , using the combination of professor and course's name.

[Kumud-Arora]

@mikehquan19 I'd like to try this!

[mikehquan19]

Cool!

[mikehquan19]

@Kumud-Arora how is it going?

[mikehquan19]

closes by #394 🎉🎉