Add `id` to Export Endpoints

[rush42]

Because we made the id a dedicated database column it was no longer available in the exports. This PR reintroduces but as the dedicated feature id weather as a property. The example bellow demonstrates this change.

Now:

{
    type: 'feature',
    id: 'way/100',
    properties: {},
    geometry: ...
}

Before:

{
    type: 'feature',
    properties: {
        id: 'way/100'
    },
    geometry: ...
}