Update/fix the existing TS declaration file

[hwillson]

This PR modernizes/fixes the existing TypeScript declaration file as follows:

• The module declaration now better represents how exports are currently setup, by using module augmentation to give access to helper functions that are added to the gql function itself.
• Backwards compatibility has been maintained by re-exporting helper functions.
• Stronger typing changes; the first param of the gql template literal is now a read only string based array, and the gql return type is a DocumentNode. We're leveraging TS' import types functionality to reference the DocumentNode type, which will help avoid issues like the previously reverted attempts to do this in Reverting #141 until we can figure out why its throwing errors. #151 and Add DocumentNode to gql declaration #196.
• While the new gql type changes could in theory be considered breaking, they really shouldn't be in practice. Tagged template literals enforce the use of an immutable array of strings, which means that even though literals was any before, the param should only ever have been an array of strings. Along the same lines, the gql function has only ever returned a DocumentNode, so moving away from the any return type should be pretty safe.

Fixes #282
Fixes #150

[SoyYoRafa]

This breaks a lot of code. It shouldn't have been published as a patch version.

export const myDoc = gql`...`

Now generates a TypeScript compilation error The inferred type of "myDoc" cannot be named without a referenced to "...graphql-tag/node_modules/graphql". This is likely not portable. A type annotation is necessary. I don't think that the code above is wrong so this PR must have created an issue.

[hwillson]

@SoyYoRafa what version of TypeScript are you using?

[SoyYoRafa]

3.7.5 with this tsconfig.json:

{
  "compilerOptions": {
    "forceConsistentCasingInFileNames": true,
    "target": "es2018",
    "module": "commonjs",
    "strict": true,
    "strictNullChecks": true,
    "noImplicitAny": true,
    "noImplicitReturns": true,
    "noImplicitThis": true,
    "noUnusedLocals": true,
    "lib": ["esnext.asynciterable", "es2018", "dom"],
    "sourceMap": true,
    "declaration": true,
    "declarationMap": true,
    "allowSyntheticDefaultImports": true,
    "experimentalDecorators": true
  }
}

[hwillson]

Thanks @SoyYoRafa - using the import type of import("graphql").DocumentNode should help avoid this error message. We haven't had any other reports of this being an issue since this PR was merged and released, so if there's any chance you can put together a small runnable repro that shows this, that would be helpful.

[SoyYoRafa]

Sure, how do you want me to share the reproduction? Pretty this is due to graphql-tag referencing the graphql package in the declaration file and not marking graphql as a dependency.