Support set Schema output/input types explicitly

[moshest]

In cases we already have the schema types defined, it would be a nice to have the Schema receive the output type and optionally the input type explicitly.

Motivation: Validate that the validator actually implement the given types exactly.

For example:

type Person {
  name: string;
  age: number;
}

type PersonInput {
  name: unknown;
  age: unknown;
}

const PersonSchema = Schema<Person, PersonInput>({
  name: unknown.string(),
  age: unknown.number(),
);

// typeof PersonSchema == (input: PersonInput) => Person;

I tried to implement it from the beginning, but I couldn't find a way to make it work nicely without breaking some functionality. Maybe it's time to give it another try.

Considerations:

• Support Schema without any type arguments
• Support giving only output type
• Support giving both output and input types
• Support async validators
• Bonus: Support IDE when Ctrl+Click on scheme field (ie. clicking on schema age: will jump to Person['age'])