Grafast: makeGrafastSchema causes error if TypeDef includes Input Type
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### Summary

makeGrafastSchema takes GraphQL type definition SDL as string as the option. If the type definition includes Input Type, it causes an error.

```typescript
grafast.makeGrafastSchema({
  plans: {},
  typeDefs: `
    type Query {
      a(a: A!): Boolean!
    }
    
    input A {
      str: String
    }
  `,
});
```

The above code causes the error:

```
Error: Schema must contain uniquely named types but contains multiple types named "A".
```

<!-- A brief summary of the problem. -->

### Steps to reproduce

Open this Stackblitz and execute `node index.js`.

https://stackblitz.com/edit/stackblitz-starters-ebtu9yzq?file=index.js

### Expected results

Returns GraphQLSchema value without error.

### Actual results

```
SCHEMA 1
Error: Schema must contain uniquely named types but contains multiple types named "A".
    at GraphQLSchema (/home/projects/stackblitz-starters-ebtu9yzq/node_modules/graphql/type/schema.js:219:15)
    at makeGrafastSchema (/home/projects/stackblitz-starters-ebtu9yzq/node_modules/grafast/dist/makeGrafastSchema.js:356:20)
    at  (file:///home/projects/stackblitz-starters-ebtu9yzq/index.js:20:11)
    at run (https://stackblitzstartersebtu9yzq-jkp5.w-corp-staticblitz.com/blitz.31ca1d38.js:40:784402)
    at _evaluate (https://stackblitzstartersebtu9yzq-jkp5.w-corp-staticblitz.com/blitz.31ca1d38.js:40:792245)

SCHEMA 2
Error: Schema must contain uniquely named types but contains multiple types named "Date".
    at GraphQLSchema (/home/projects/stackblitz-starters-ebtu9yzq/node_modules/graphql/type/schema.js:219:15)
    at makeGrafastSchema (/home/projects/stackblitz-starters-ebtu9yzq/node_modules/grafast/dist/makeGrafastSchema.js:356:20)
    at  (file:///home/projects/stackblitz-starters-ebtu9yzq/index.js:31:11)
    at run (https://stackblitzstartersebtu9yzq-jkp5.w-corp-staticblitz.com/blitz.31ca1d38.js:40:784402)
    at _evaluate (https://stackblitzstartersebtu9yzq-jkp5.w-corp-staticblitz.com/blitz.31ca1d38.js:40:792245)
```

### Additional context

- grafast: `0.1.1-beta.20`

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      operating system, Node, PostgreSQL, Redis, etc. as relevant), software
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### Possible Solution

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