Classify call types - Part 2

Overview

This PR contains the finalized UI for the call type classifications.

Fixes part of #10

Implemented design as defined in Figma
Added two new columns to the classifications table: confidence_rating and confidence_reasoning
Created two stimulus controllers to deal with dynamic UI changes:
- filter_controller.js to handle the automatic filtering of incident types based on the user input in the search bar (which loads data from the server0
- classify_controller.js to handle the rest of the incident type selection (which mostly happens on the client until the form is submitted)
- I originally had 4 controllers but it was honestly pretty confusing so I refactored the code to end up with 2 that match the two main components of the page (the search + filtering and the selection steps)
I don't have too much to describe here since it's mostly UI changes (HTML & JS)

Here's a demo:

In the last part, I will be focusing on adding the data set completion and the categorization rules:

[x] implement data set completion logic and UI
[x] sort data set by completion
[x] categorization rules
- [x] Data that has been once but not 3 times should be displayed first
- [x] Data that has been categorized three times should not be presented again
- [x] The same categorizer should not be able to categorize the same item twice
- [x] The user that made the categorization should be captured

I will also be adding tests for the whole flow:

[ ] call_types_controller (index & create)
[ ] common incident types controller (search)
[ ] features specs: classification flow (unknown, back, proceed, test different confidence level)