Type mismatch describer should expand aliases

When a type mismatch occurs against a type alias, the type alias is reported as expected, and then the value is shown. This means that it is hard for the user to understand what is wrong without searching for documentation of that type alias.

The type mismatch explainer needs to include the alias expansion.

type OhDeer = Enum[rudolph, dasher,  dancer, prancer, vixen, comet, cupid, dunder, blixem,]

function pull_sled(OhDeer $a_deer) { }

pull_sled('blixen')

If you, like most, do not remember all of Santa's raindeers, you need to see the enum expanded to learn how to spell 'blixem'