Add mapbox density charts

Author: Hao Tran

docs/manuals/gui/viselements/charts/mapbox-air-index-dark.png

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+## Mapbox density charts
+
+This type of chart creates maps where density can be displayed. 
+
+
+### Basic Mapbox Density Chart - Air Quality Index
+
+In this example, we will visualize the air quality index at 3 locations on map. Bigger circle will have worse air quality.
+
+```py
+data = {
+  "lon": [10, 20, 30], 
+  "lat": [15, 25, 35], 
+  "air_index": [7, 20, 10]
+}
+
+layout = {
+  "mapbox": {
+      "style": "open-street-map"
+  }
+}
+```
+!!! example "Page content"
+
+    === "Markdown"
+
+        ```
+        <|{data}|chart|lon=lon|lat=lat|z=air_index|type=densitymapbox|layout={layout}|>
+        ```
+
+    === "HTML"
+
+        ```html
+        <taipy:chart type="densitymapbox" lon="lon" lat="lat" z="air_index" layout="layout">{data}</taipy:chart>
+        ```
+
+<figure>
+    <img src="mapbox-air-index-dark.png" class="visible-dark" />
+    <img src="mapbox-air-index.png" class="visible-light" />
+    <figcaption>Air Quality Index</figcaption>
+</figure>
+
+### World Map with Earthquake Magnitude
+
+
+```py
+df = pandas.read_csv(
+    'https://raw.githubusercontent.com/plotly/datasets/master/earthquakes-23k.csv')
+
+opts = {
+    "coloraxis": 'coloraxis',
+    "hoverinfo": 'skip',
+    "radius": 5
+}
+
+layout = {
+    'mapbox': {
+        'style': 'stamen-terrain'
+    },
+    "coloraxis": {
+        "colorscale": "Viridis"
+    }, 
+    "title": {
+        "text": "Earthquake Magnitude"
+    }
+}
+```
+!!! example "Page content"
+
+    === "Markdown"
+
+        ```
+        <|{df}|chart|type=densitymapbox|lat=Latitude|lon=Longitude|z=Magnitude|options={opts}|layout={layout}|>
+        ```
+
+    === "HTML"
+
+        ```html
+        <taipy:chart type="densitymapbox" lat="Latitude" lon="Longitude" z="Magnitude" options="opts" layout="layout">{df}</taipy:chart>
+        ```
+
+<figure>
+    <img src="mapbox-earthquake-magnitude-dark.png" class="visible-dark" />
+    <img src="mapbox-earthquake-magnitude.png" class="visible-light" />
+    <figcaption>World Map with Earthquake Magnitude</figcaption>
+</figure>
+
+Explanation of parameters and options relevant to Mapbox density charts can be found [here](https://plotly.com/javascript/reference/densitymapbox/). Full details for the Taipy Chart control can be found in the Chart Control section of the [Taipy GUI User Manual](https://docs.taipy.io/en/latest/manuals/gui/viselements/chart/)
+
+### Key parameters
+| Parameter       | Value Options             | Location           |
+| --------------- | ------------------------- | ------------------ |
+| type          | "densitymapbox"          | Control definition |
+| lon | Column name for longitudes | Control definition |
+| lat | Column name for latitudes | Control definition |
+| z | Column name for density | Control definition |
+| mapbox | Dictionary of parameters for maps (style). [More details](https://plotly.com/javascript/mapbox-layers/) | Layout |
+| radius | int | Options |
+| coloraxis | Dictionary (colorscale) | Layout+Options |