pid: zone split out builders

To enable unit-testing, split the builders into their own
object files.

Tested: Ran on quanta-q71l board and it behaved as expected.

Change-Id: I92168ec9ae4946d12328e9c0b94a36bb89d0f718
Signed-off-by: Patrick Venture <venture@google.com>
diff --git a/pid/builder.hpp b/pid/builder.hpp
new file mode 100644
index 0000000..5c03bd1
--- /dev/null
+++ b/pid/builder.hpp
@@ -0,0 +1,14 @@
+#pragma once
+
+#include <memory>
+#include <sdbusplus/bus.hpp>
+#include <unordered_map>
+
+#include "pid/zone.hpp"
+#include "sensors/manager.hpp"
+
+std::unordered_map<int64_t, std::unique_ptr<PIDZone>> BuildZones(
+        std::map<int64_t, PIDConf>& zonePids,
+        std::map<int64_t, struct zone>& zoneConfigs,
+        SensorManager& mgr,
+        sdbusplus::bus::bus& modeControlBus);