Add the new aggregate pipeline that group all the sections by the combination of course and professor

[mikehquan19]

Currently to address Trend's need, we've written 2 pipelines in /uploader/pipelines/trends_prof_sections & /uploader/pipelines/trends_course_sections. What do they do?

They insert the aggregated sections data directly to the database, so that Trends can query the sections without exceeding the number of API calls imposed by Vercel.

TrendsProfSectionsPipeline will aggregate data into format:

profFirst + profLast: {
   Section, 
   Section, 
   ...
}

TrendsCourseSectionsPipeline will aggregate data into format:

prefix + number: {
   Section, 
   Section, 
   ...
}

Now, in order to improve their search quality even further, I'm proposing another pipeline that can aggregate data into this format:

prefix + number + profFirst + profLast: {
   Section, 
   Section, 
   ...
}