Fabric: `fromDynamic`: Parsing vector type when source has no array
Fabric: `fromDynamic`: Parsing vector type when source has no array

Summary:
@public
If some prop has `std::vector` type, it possible that on JS side we want to pass just one element of the array.
And in this case we sometimes drop array initialization (`[]`) part, so instead of passing `[{x:1, y:1}]` we pass `{x:1, y:1}`.
This diff adds support for that.

Reviewed By: mdvacca

Differential Revision: D8526572

fbshipit-source-id: 33d4369ac48cac3eb1c534f477d8259e76e0c547

janicduplessis/react-native,janicduplessis/react-native,exponentjs/react-native,janicduplessis/react-native,javache/react-native,hammerandchisel/react-native,exponentjs/react-native,exponent/react-native,myntra/react-native,hoangpham95/react-native,facebook/react-native,janicduplessis/react-native,hoangpham95/react-native,myntra/react-native,hoangpham95/react-native,janicduplessis/react-native,exponent/react-native,janicduplessis/react-native,hoangpham95/react-native,pandiaraj44/react-native,pandiaraj44/react-native,facebook/react-native,pandiaraj44/react-native,javache/react-native,hoangpham95/react-native,javache/react-native,facebook/react-native,arthuralee/react-native,exponentjs/react-native,myntra/react-native,hoangpham95/react-native,hammerandchisel/react-native,hammerandchisel/react-native,pandiaraj44/react-native,janicduplessis/react-native,hoangpham95/react-native,exponent/react-native,arthuralee/react-native,hammerandchisel/react-native,myntra/react-native,myntra/react-native,javache/react-native,exponent/react-native,facebook/react-native,arthuralee/react-native,exponentjs/react-native,hammerandchisel/react-native,arthuralee/react-native,hammerandchisel/react-native,javache/react-native,pandiaraj44/react-native,facebook/react-native,hammerandchisel/react-native,facebook/react-native,facebook/react-native,myntra/react-native,exponent/react-native,javache/react-native,exponent/react-native,myntra/react-native,janicduplessis/react-native,pandiaraj44/react-native,facebook/react-native,exponentjs/react-native,facebook/react-native,myntra/react-native,arthuralee/react-native,pandiaraj44/react-native,exponent/react-native,myntra/react-native,hoangpham95/react-native,pandiaraj44/react-native,javache/react-native,javache/react-native,exponentjs/react-native,hammerandchisel/react-native,javache/react-native,exponentjs/react-native,exponentjs/react-native,exponent/react-native