Adds city subdirectories for crops

[misaugstad]

Resolves #3502

Crops will now be split into subdirectories based on their city and label type. Instead of crop_temp_<city-id>_<user-id>_<temp-label-id>_<label-type>.png, they will be stored as <city-id>/<label-type>/crop_temp_<user-id>_<temp-label-id>.png.

Once this is on the servers, I will just need to run the following script to update all past data:

#!/bin/bash

# Prevents errors when no files are found.
shopt -s nullglob

# Loop over all cities.
for city in seattle-wa columbus-oh cdmx spgg pittsburgh-pa newberg-or chicago-il amsterdam la-piedad oradell-nj validation-study zurich taipei new-taipei-tw keelung-tw auckland cuenca crowdstudy burnaby teaneck-nj walla-walla-wa; do
    # Loop over all label types.
    for label_type in CurbRamp NoCurbRamp Obstacle SurfaceProblem NoSidewalk Crosswalk Signal Occlusion Other; do
        # Create the necessary dir.
        mkdir -p "${city}/${label_type}"

        # Loop over all files matching the pattern if any exist.
        for file in crop_temp_${city}_*_${label_type}.png; do
            # Extract the piece of the filename that we keep.
            user_and_temp_id=$(basename "$file" | sed "s/crop_temp_${city}_\(.*\)_${label_type}\.png/\1/")

            # Construct the destination path.
            dest_path="${city}/${label_type}/crop_temp_${user_and_temp_id}.png"

            # Move the file.
            mv "$file" "$dest_path"
        done
    done
done

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