Add zoom/scale expression

[jansule]

Feature Request

Is your feature request related to a problem? Please describe.

Some formats/styles may contain zoom/scale based expressions that are currently not supported in geostyler-style.

E.g. see following mapbox snippet:

"paint": {
      "line-width": [
          "interpolate",
          ["linear"],
          ["zoom"], // <--------- zoom level as input for the interpolate expression
          12,
          2,
          15,
          4,
          19,
          35
      ]
}

Describe the solution you'd like

It would be great to include this into geostyler-style.

Please note that SLD does not seem to support zoom/scale based expressions. There, the scaleDenominators seem to be the only way of handling different styles based on zoom/scale.

Describe alternatives you've considered
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Additional context
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