feat: Select road level of precision

[ThomasParistech]

Description

• Built on top of feat: add a dropdown to select priority to plot #91 from @JulesL2
• Merge CityRoadType and RoadPrecisionLevel as they're equivalent
• Download all the roads at the init, to keep the same logic as for the union of paper sizes and avoid requesting several times for the additional roads. And filter them at drawing time
• Add UiDropdown component similar to UiToggle
• Improve doc of UI components

Corresponding Github Issues / Pull Requests

• PR feat: add a dropdown to select priority to plot #91
• Issue London and Paris Marathon are quite heavy (25MB) #59

Proof of Functionality

Provide evidence that the changes work as intended. Include screenshots, logs, or other relevant output.

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