proc,service: expose goroutine pprof labels in api

Labels can help in identifying a particular goroutine during debugging.

Fixes #1763

service/api/types.go

@@ -308,6 +308,8 @@ type Goroutine struct {
 	// ID of the associated thread for running goroutines
 	ThreadID   int    `json:"threadID"`
 	Unreadable string `json:"unreadable"`
+	// Goroutine's pprof labels
+	Labels map[string]string `json:"labels,omitempty"`
 }
 
 // DebuggerCommand is a command which changes the debugger's execution state.