Style spec validator allows any `string` as a value for `projection` field

Style-spec validator allows projection to be a string which is not supported by the spec itself. The spec states that it should be an object with a name field.

This line is the source of the problem: https://github.com/mapbox/mapbox-gl-js/blob/5859fd8103adc1781e047d89189d7e5f96f5df9a/src/style-spec/validate/validate_projection.js#L29

Somewhat related: https://github.com/mapbox/mapbox-gl-js/issues/12028

This page in the documentation describes where shorthand is appropriate. It seems like it should never be present in a style.

const token = 'pk.eyJ1IjoiYWxleGFuZGVyLWJlbG9rb24iLCJhIjoiY2w3Z2R0cTRiMDNmZTN2b2E1NTNoZGVsOCJ9.UJGcVwpGNY34ApOhnkw4wg'
mapboxgl.accessToken = token

async function create() {
  const res = await fetch(`https://api.mapbox.com/styles/v1/mapbox/streets-v11?access_token=${token}`)
  const style = await res.json()

  // works
  const map1 = new mapboxgl.Map({ container: 'map1', style: { ...style }, projection: 'globe' })
  
  // doesn't work
  const map2 = new mapboxgl.Map({ container: 'map2', style: { ...style, projection: 'globe' } })
}
create()

mapbox-gl-js version: 2.10.0

browser: any

Steps to Trigger Behavior

1. create a style with { "projection": "chair" }
2. try to validate it
3. observe return value

Link to Demonstration

JSBin

Expected Behavior

Validator rejects string values for the projection field

Actual Behavior

Validator allows string values for the projection field

Start with src/style-spec/validate/validate_projection.js at the linked line, then compare its accepted values with the projection definition in src/style-spec/reference/v8.json. Run the validation steps from the issue with a string projection and an object projection; done means the validator rejects string values for projection while preserving the supported object form.