Adding voting locations to Chicago maps (temporarily)

[misaugstad]

Brief description of problem/feature

Through conversations with @yeisenberg: we are working with a disability group in Chicago, and a pilot that we want to try out is to audit some routes to polling stations and visualize the data on LabelMap. @yeisenberg sent me the polling locations:
Voting_accessibility_locations_M2023.zip

Here's what I think needs to be done:

1. Add the polling locations to RouteBuilder so that we can create routes around those polling locations for people to audit. I'll looks for some polling location icon online that I can use! Issue #3689 is the more general feature we'd like to add, but on short notice I'll manually add them myself in Chicago (and we will remove them later).
2. Add the polling locations to LabelMap as well
3. Add the ability to view just the data along a route in LabelMap (#3434), probably just with a URL parameter to start. Time permitting, I'd add a button to RouteBuilder so that, once you create a route, you can immediately go and view it in LabelMap.