Simplify layout/paint property types
Simplify layout/paint property types

Types were made more specific to add extra type safety around constants.
Without constants, we no longer need these more specific types. Fewer,
well-known types makes tooling support easier.

- '*-enum' -> 'enum'
- '*-array' -> 'array'
- 'opacity' -> 'number'
- 'field-template' -> 'string'

pka/mapbox-gl-style-spec,pka/mapbox-gl-style-spec