Move category file into a prop of preset

[tordans]

Right now, the category a preset belongs to is handled in a separate file.
Whenever we add presets, we need to remember to update those lists.
Instead, we could make this a prop of the preset.

See openstreetmap/id-tagging-schema#1916 (comment) where we noticed that some where missing and discussed the sort order.

Advantage: Easy to see remember whenever we work on the preset.
Disadvantage: We need to find a different way to sort the presets (now it is the order of the category-array; could be usage stats or just A-Z or a weight prop).

Possible code…

{
  categories: [ 
    { key: 'playground', weight: 1.1 } 
  ]
}

{
  categories: { 
    playground: 1.1 
  }
}