Make usePrometheus available from @graphql-mesh/plugin-prometheus

[klippx]

Description

usePrometheus is not available to import from @graphql-hive/gateway:

import { 
  useJWT, 
  useOpenTelemetry,
  // usePrometheus // Not available!
} from '@graphql-hive/gateway';
import usePrometheus from '@graphql-mesh/plugin-prometheus';

With this PR, it will be possible to:

import { 
  useJWT, 
  useOpenTelemetry,
  usePrometheus,
} from '@graphql-hive/gateway';

Type of change

• New feature (non-breaking change which adds functionality)

[ardatan]

Covered here;
graphql-hive/gateway#87