Add support for numeric literal types

[jc-1234]

We have a component with a size prop of numeric literal type.
size?: 14 | 20 | 24 | 32 | 48;

It would be nice to have native support for a knob that can take in a list of values. We already have a documentation tool that tells us the possible values for literal types. We want the same behavior as Enum PropType but currently Enum only works with string literal type.