feat(pprof): add pprof HTTP server (#807)

- `PPROF_ENABLED=no`
- `PPROF_BLOCK_PROFILE_RATE=0`
- `PPROF_MUTEX_PROFILE_RATE=0`
- `PPROF_HTTP_SERVER_ADDRESS=":6060"`

internal/httpserver/address.go

@@ -0,0 +1,7 @@
+package httpserver
+
+// GetAddress obtains the address the HTTP server is listening on.
+func (s *Server) GetAddress() (address string) {
+	<-s.addressSet
+	return s.address
+}