feat: add screenshot tests for the topo-raster tileset BM-1167

[tawera-manaena]

Motivation

As a Basemaps developer, I want screenshot tests that capture changes to the Basemaps NZ Topo Gridless Maps layer (topo-raster tileset). We anticipate refactoring the process that generate the layer's imagery. We will undertake such refactoring efforts when we come to support additional Map Series datasets, such as:

• New Zealand Outer Islands (NZOI)
• Pacific Islands (PI)

Having these tests will help us automatically identify artifact concerns and unanticipated changes that may arise due to changes to the imagery generation process.

Modifications

This work adds three new screenshot tests:

nz-topo-gridless-maps-2193-nz-250k-z4
Verifies the absence of black edge artifacts around the imagery's perimeter [1].

nz-topo-gridless-maps-3857-chatham-islands-250k-z10
Verifies the location and re-projection of the Chatham Islands imagery from EPSG:3793 to EPSG:3857 [2].

nz-topo-gridless-maps-3857-wellington-50k-z12
Verifies the tileset displays the 50k imagery as defined in the tileset's definition [3].

Verification

I have verified the added screenshot tests locally. I used the following commands to install the required dependencies and compile the source code:

# install dependencies
npm install

# compile the source code
npm run build

I then used the following command to run the screenshot process:

# run the screenshot process
node build/src/bin.js --url basemaps.linz.govt.nz --output screenshot-folder/

The process captures the added screenshot tests and saves them to the output location without issue.