No synthetic Awaited for unconstrained type when not a type variable

[rbuckton]

await should only produce Awaited<T> when T's base constraint is any, unknown, {}, or object, or when T is an unconstrained generic. Prior to this change, a Record type with a generic key would satisfy the isGenericObjectType condition, but would have no base constraint, resulting in the introduction of an unnecessary Awaited wrapper around the type.

Fixes #47144