Batch Checks in OpenFGA Server

[aaguiarz]

We currently support issuing checks in batch in the OpenFGA SDKs. This works by issuing checks in parallel, and we believe it's a good approach in general.

When you deploy OpenFGA with multiple nodes, the load can be spread across nodes, and the total response time would be close to the response time of the most expensive check call.

However, when the number of checks is too large, it could be useful to resolve all the checks in the server with a single roundtrip.