enable line numbers for ghr (#4611)

Line number support is opt-in on a per-source basis. This commit opts GitHub Real-time into the system.

Author: rosecodym

pkg/engine/engine.go

@@ -1266,6 +1266,7 @@ func SupportsLineNumbers(sourceType sourcespb.SourceType) bool {
 	switch sourceType {
 	case sourcespb.SourceType_SOURCE_TYPE_GIT,
 		sourcespb.SourceType_SOURCE_TYPE_GITHUB,
+		sourcespb.SourceType_SOURCE_TYPE_GITHUB_REALTIME,
 		sourcespb.SourceType_SOURCE_TYPE_GITLAB,
 		sourcespb.SourceType_SOURCE_TYPE_BITBUCKET,
 		sourcespb.SourceType_SOURCE_TYPE_GERRIT,