codeintel: Batch code intelligence queries
Created by: efritz
This PR introduces a new batch GraphQL resolver for precise code intelligence. This will be used in the code intelligence extensions (implemented in https://github.com/sourcegraph/code-intel-extensions/pull/414).
This new resolver returns intra-bundle code intelligence (anything resolvable without looking outside the current bundle) for all ranges within a span of lines. This gives the code intel extension enough context that useful results can be loaded instantaneously (without additional network calls) when the user hovers over other variables what is (likely) currently visible in the blob.
This implements the backend required to close https://github.com/sourcegraph/sourcegraph/issues/10869.