feat: Allow enums to be remapped like scalars

[kitten]

Resolves #180

Summary

This allows enums to be remapped like scalars. Specifically, if a user has a more qualified type for enums, they should be allowed to completely remap it.

Because Omit<Schema['types'], keyof Scalars> is potentially expensive for TypeScript to traverse, this PR avoids this pattern and instead refactors the code that resolves the types for enums. Specifically, mapEnum now outputs its type onto the enumValues property rather than type.

This PR also removes some redundant checks throughout the touched code path.

In practice, the following is now possible:

enum TestEnum {
  value = 'VALUE',
  test = 'TEST',
}

const graphql = initGraphQLTada<{
  introspection: someIntrospection;
  scalars: {
    // enum Test { VALUE, TEST }
    Test: TestEnum;
  };
}>();

In the future, we could add an additional check to graphql.scalar that checks the remapped type against the enumValues type to make sure they're compatible.

Set of changes

• Refactor getInputObjectTypeRec and _getVariablesRec in variables.ts to move obj<> squashing
• Remove SCALAR and ENUM markers from processed schema outputs
• Remove redundant unknown | never output from processed schema outputs
• Slim down introspection generics once again
• Allow scalars to be an object of readonly properties
• Output enum type onto enumValues and modify variables.ts and selection.ts to check type then enumValues

[changeset-bot]

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Latest commit: 9314abd

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