Structured logging rebased

_support/fake-auth-backend.go

internal/artifacts/artifacts_test.go

internal/artifacts/entry.go

internal/git/blob.go

internal/git/diff.go

internal/git/format-patch.go

internal/helper/accesslogformatter.go

internal/helper/accesslogformatter_test.go

internal/helper/clock.go

internal/helper/helpers.go

internal/helper/logging.go

internal/helper/logging_test.go

internal/redis/keywatcher.go

internal/redis/redis.go

internal/sendfile/sendfile.go

internal/sendurl/sendurl.go

internal/staticpages/servefile.go

internal/terminal/terminal.go

internal/testhelper/gitaly.go

internal/testhelper/testhelper.go