Plugins: Add statusSource to partial data response error log (#78057)

* Plugins: Add statusSource to partial data response error log

* Introduce DefaultStatusSource

* Add StatusSourceFromPluginErrorSource

* Moved StatusSourceFromPluginErrorSource

* Update pkg/services/pluginsintegration/clientmiddleware/logger_middleware.go

pkg/plugins/pluginrequestmeta/plugin_request_meta.go

@@ -3,6 +3,8 @@ package pluginrequestmeta
 import (
 	"context"
 	"errors"
+
+	"github.com/grafana/grafana-plugin-sdk-go/backend"
 )
 
 // StatusSource is an enum-like string value representing the source of a
@@ -14,16 +16,19 @@ const (
 	StatusSourceDownstream StatusSource = "downstream"
 )
 
+// DefaultStatusSource is the default StatusSource that should be used when it is not explicitly set by the plugin.
+const DefaultStatusSource StatusSource = StatusSourcePlugin
+
 type statusSourceCtxKey struct{}
 
 // StatusSourceFromContext returns the plugin request status source stored in the context.
-// If no plugin request status source is stored in the context, [StatusSourcePlugin] is returned.
+// If no plugin request status source is stored in the context, [DefaultStatusSource] is returned.
 func StatusSourceFromContext(ctx context.Context) StatusSource {
 	value, ok := ctx.Value(statusSourceCtxKey{}).(*StatusSource)
 	if ok {
 		return *value
 	}
-	return StatusSourcePlugin
+	return DefaultStatusSource
 }
 
 // WithStatusSource sets the plugin request status source for the context.
@@ -42,3 +47,13 @@ func WithDownstreamStatusSource(ctx context.Context) error {
 	*v = StatusSourceDownstream
 	return nil
 }
+
+// StatusSourceFromPluginErrorSource takes an error source returned by a plugin and returns the corresponding
+// StatusSource. If the provided value is a zero-value (i.e.: the plugin did not set it), the function returns
+// DefaultStatusSource.
+func StatusSourceFromPluginErrorSource(pluginErrorSource backend.ErrorSource) StatusSource {
+	if pluginErrorSource == "" {
+		return DefaultStatusSource
+	}
+	return StatusSource(pluginErrorSource)
+}