Add section filters

[Anzhuo-W]

Purpose

In returned results, only show specific sections that match all filters of the classes with at least one section that matches filters.

Before:

After:

Tickets

Addresses #233

Contributors

@Anzhuo-W

Feature List

When campus filters are applied, sections are only displayed for that campus instead of all sections for a course where at least one section is on that campus. The sections are filtered out from the results after they are returned by query; additionally applies to honors sections, class type, and subject.

Reviewers

Primary reviewer:
@ananyaspatil

Secondary reviewers:
@nickpfeiffer05 @cherman23 @mehallhm

[coveralls]

coverage: 80.173% (-0.4%) from 80.533%
when pulling c8c5ada on filter-out-sections
into 6cd914e on master.

[mehallhm]

I wish there wasn't a way to iterate over everything multiple times, but I have no ideas rn. Depending on merge order, this might lightly conflict with Nick's #235