Host metrics (#6817)

* Add std::string exec() function to PortduinoGlue for future work

* MVP for HostMetrics module.

* Fix compilation for other targets

* Remove extra debug calls

* Big numbers don't do well as INTs.

* Add HostMetrics to config.yaml

src/modules/Telemetry/HostMetrics.h

@@ -0,0 +1,40 @@
+#pragma once
+#include "../mesh/generated/meshtastic/telemetry.pb.h"
+#include "ProtobufModule.h"
+
+class HostMetricsModule : private concurrency::OSThread, public ProtobufModule<meshtastic_Telemetry>
+{
+    CallbackObserver<HostMetricsModule, const meshtastic::Status *> nodeStatusObserver =
+        CallbackObserver<HostMetricsModule, const meshtastic::Status *>(this, &HostMetricsModule::handleStatusUpdate);
+
+  public:
+    HostMetricsModule()
+        : concurrency::OSThread("HostMetrics"),
+          ProtobufModule("HostMetrics", meshtastic_PortNum_TELEMETRY_APP, &meshtastic_Telemetry_msg)
+    {
+        uptimeWrapCount = 0;
+        uptimeLastMs = millis();
+        nodeStatusObserver.observe(&nodeStatus->onNewStatus);
+        setIntervalFromNow(setStartDelay()); // Wait until NodeInfo is sent
+    }
+    virtual bool wantUIFrame() { return false; }
+
+  protected:
+    /** Called to handle a particular incoming message
+    @return true if you've guaranteed you've handled this message and no other handlers should be considered for it
+    */
+    virtual bool handleReceivedProtobuf(const meshtastic_MeshPacket &mp, meshtastic_Telemetry *p) override;
+    // virtual meshtastic_MeshPacket *allocReply() override;
+    virtual int32_t runOnce() override;
+    /**
+     * Send our Telemetry into the mesh
+     */
+    bool sendMetrics();
+
+  private:
+    meshtastic_Telemetry getHostMetrics();
+
+    uint32_t lastSentToMesh = 0;
+    uint32_t uptimeWrapCount;
+    uint32_t uptimeLastMs;
+};