codeintel: Index queue client
Created by: efritz
This PR implements part of RFC 199: Arbitrary code execution in the auto-indexer and closes https://github.com/sourcegraph/sourcegraph/issues/12665.
This PR adds a client for the new endpoints that were added in https://github.com/sourcegraph/sourcegraph/pull/12657 for use by a new precise-code-intel-indexer service that manages tasks within firecracker VMs.