Rule protecting against batching requests

[ldebruijn]

Is your feature request related to a problem? Please describe.
Implement a rule that protects the API against GraphQL Batching Attacks

Describe the solution you'd like
Provide a protection that poses a limit on the maximum size of batches

Describe alternatives you've considered
The existing max token protection already protects against batch attacks, but doesn't do so sufficiently as the need for support of large operations might collide with vulnerability to tiny operations in large batches.

Additional context
Batch request format

[
 {
   "query": "< query 0 >",
   "variables": { < variables for query 0 >, }
 },
 {
  "query": "< query 1 >",
  "variables": { < variables for query 1 >, }
 },
 {
 "query": "< query n >",
 "variables": { < variables for query n >, }
 }
]

Response format

[
  {
    “data”: { < ... >}
  },
  {
    “data”: { < ... > }
  },
]