feat(landing): adjust layers dropdown BM-1079

[tawera-manaena]

Motivation

As a Basemaps user, I want the Topolite layer and the Scanned Aerial Imagery Basemaps category to appear at the top of the Layers dropdown for easier access.

Modifications

1. Reordered the categories as they are shown in the Layers dropdown.
2. Added the Topolite layer to the list of default layers.

Verification

1. Moved the Scanned Aerial Imagery Basemaps category to the top of the Layers dropdown below the Basemaps category.

Before	After

2. Added the Topolite layer to the list of default layers.

Before	After

3. When the user selected the Topolite layer:

The StyleJSON and XYZ fields display the expected values.

The style parameter in the URL reflects the intended value.
.../@-41.8899962,174.0492437,z5?style=topolite&i=topographic