Support GQL Get{} tunable consistency

[parkerduckworth]

Introduces client.graphql.get().withConsistencyLevel() to set desired consistency level per query.

Example:

import weaviate, { WeaviateClient } from 'weaviate-ts-client';

const client: WeaviateClient = weaviate.client({
  scheme: 'http',
  host: 'localhost:8080',
});

const resp = await client.graphql
  .get()
  .withClassName('Article')
  .withFields('_additional { id isConsistent }')
  .withConsistencyLevel('ONE')
  .do();

console.log(`resp: ${JSON.stringify(resp)}`);