Migrate graphqlbackend.RepositoryResolver to use sg/log

Created by: gitstart-sourcegraph

Description

Add a logger to schemaResolver, and initialize it with log.Scoped (or logtest where appropriate) wherever schemaResolver is created (unless an existing logger is easily available, in which case that should be used) Add a logger to RepositoryResolver, and let it be injected from NewRepositoryResolver. Use log.Scoped (or logtest where appropriate) to provide the logger at all usages of NewRepositoryResolver 3 log15 usages inside cmd/frontend/graphqlbackend/repository.go are replaced with calls to the appropriate logger

Test plan

• A good way to test this PR is just to run the branch locally, and open the issue link, compare the changes on the PR and the listed issues. All of them must be fixed

Refs

• SourceGraph Issue
• GitStart ticket