Feature: batch evaluate exclude not found

[itaischwartz]

Add an option to exclude not-found flags from batch evaluate calls.

This change makes it possible to separate flags management from client calls.

• a client can add a flag to the batchEvaluateRequest list even before the flag was added.
• admin can remove flags w/o having to worry about batchEvaluate calls failing altogether.

[itaischwartz]

@markphelps
We can think of a new version of batchEvaluate (batchEvaluteV2) where we expose a separate error value for each flag in responseList, and let the client choose how to handle the error.

[markphelps]

Great idea @itaischwartz ! Thanks for the contribution. Just one minor request re: tests.

I agree maybe a new API method is needed to add an error to each evaluation request/response.

[markphelps]

would you mind adding another test where ExcludeNotFound is false or simply not set (so it defaults to false)?

[itaischwartz]

I think that TestEvaluate_FlagNotFound is testing this case.

[itaischwartz]

I see now that it's testing another grpc call.
I'll add the missing test case

[itaischwartz]

done

[markphelps]

@all-contributors please add @itaischwartz for code

[allcontributors]

@markphelps

I've put up a pull request to add @itaischwartz! 🎉

[markphelps]

Awesome! Thanks again!