Datasets - Allow a menu config item, for more complex menus

[markfee]

The menu is currently derived from the datasets config, but sometimes the menu is more complex than that approach allows.

This ticket will also define a menu config structure, such that:

• The menu config will be stored in pluginState, if provided
• If not provided, the pluginState.menu will be derived from the datasets config
• The 'Menu' will be rendered directly from the pluginState.menu config
• The datasets will derive their visibility from the pluginState.menu, if showInMenu is true in the datasets config.

[markfee]

Example menu config:

const menu = [
  {
    id: 'dataset',
    label: 'Datasets',
    // urlKey: 'dataset', // use a default of the id here if the urlKey is the same as the id, to save repetition
    visibleWhen: true,
    type: 'radio', // 'checkbox' or 'radio'
    value: 'floodzones', // this is the default value for the menu, it should be one of the items' id
    items: [
      { id: 'floodzones', label: 'Flood zones', checked: true },
      { id: 'surfacewater', label: 'Surface water' },
      { id: 'none', label: 'None', },
    ],
  },
  {
    id: 'timeframe',
    label: 'Timeframe',
    urlKey: 'dataset', // dataset=floodzones&timeframe=presentday
    urlIndex: 1, //surfacewater-presentday-high-depth
    type: 'radio',
    visibleWhen: { dataset: ['floodzones', 'surfacewater'] },
    value: 'presentday',
    items: [
      { id: 'presentday', label: 'Present day', },
      { id: 'climatechange', label: '2070 to 2125', visibleWhen: { dataset: ['floodzones'] } },
      { id: 'climatechange', label: '2061 to 2125', visibleWhen: { dataset: ['surfacewater'] } },
    ]
  }, {
    id: 'aep',
    label: 'Annual likelihood of flooding',
    urlKey: 'dataset',
    urlIndex: 2,
    type: 'radio',
    visibleWhen: { dataset: ['surfacewater'] },
    value: 'medium',
    items: [
      { id: 'high', label: '1 in 30' },
      { id: 'medium', label: '1 in 100' },
      { id: 'low', label: '1 in 1000' },
    ]
  }, {
    id: 'depth',
    label: 'Depth',
    urlKey: 'dataset',
    urlIndex: 3,
    type: 'radio',
    visibleWhen: { dataset: ['surfacewater'] },
    subMenu: true,
    value: 'depthAll',
    items: [
      { id: 'depthAll', label: 'All depths', },
      { id: 'depth150', label: 'Full extent of flooding', },
      { id: 'depth300', label: 'Extent over 150mm', },
      { id: 'depth600', label: 'Extent over 300mm', },
      { id: 'depth900', label: 'Extent over 600mm', },
      { id: 'depth1200', label: 'Extent over 900mm', },
      { id: 'depth2300', label: 'Extent over 1200mm', },
      { id: 'depthOver2300', label: 'Extent over 2300mm', },
    ]
  }, {
    id: 'features',
    label: 'Map features',
    urlKey: 'features',
    type: 'checkbox',
    visibleWhen: true,
    items: [
      { id: 'water-storage', label: 'Water storage', checked: false },
      { id: 'flood-defence', label: 'Flood defence', checked: false },
      { id: 'main-rivers', label: 'Main rivers', checked: false },
    ]
  }
]