codeintel: Call ResolveRev to distinguish gitserver errors

Created by: efritz

The gitserver client used for codeintel does not currently distinguish a failing git command from a bad object response, which is common in codeintel as we keep references to commits which may become unreachable.

This simply adds a ResolveRev call after each failing command that supplies a specific revision. This should return the correct error now as the output is parsed from this function correctly.

Filing https://github.com/sourcegraph/sourcegraph/issues/16933 to keep track of the debt that is this package.