[typescript-graphql-request] allow custom Sdk type

[eth3lbert]

Is your feature request related to a problem? Please describe.

Currently, @graphql-codgen/typescript-graphql-request uses a hard-coded Sdk type. If the schema also has a Sdk type, this will cause a conflict.

Describe the solution you'd like

Allow the user to customize the Sdk type, for example by adding the sdkType option to the configuration.

[eth3lbert]

Could also fix via hooks:

  hooks: {
    afterOneFileWrite: [
      `sed -i -e "s|export type Sdk = ReturnType|export type MySdk = ReturnType|g"`,
    ]
  }