Added buildSchema config

[Edsol]

Added configuration to buildSchema to disable creation of mutations

[Sukairo-02]

Is it necessary though? You could already disable mutations (or, any query at all) by using custom schema with reused types\resolvers. Is it that much more convenient to pass a flag instead?

[Edsol]

rather than starting with manual schema construction, I am trying to create an automatic generator from an existing database (see here).

I did something like this to generate a mutationless schema:

const noMutationsSchema = new GraphQLSchema({
    query: schema.getQueryType(),
    subscription: schema.getSubscriptionType(),
  });

it seems unnecessary to me to generate a new scheme, I have not found a faster alternative solution.

[Sukairo-02]

I see, that's more convenient it seems. I'll be adding ability do enable\disable queries (UPD: that crashes schema, will stick to mutations only) to that as well, thanks for your contribution.