Reduce key duplication by enabling hardware RNG (#8803)

* Reduce key duplication by enabling hardware RNG

* Apply suggestion from @Copilot

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

* Apply suggestion from @Copilot

Use micros() for worst case random seed for nrf52

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

* Minor cleanup, remove dead code and clarify comment

* trunk

* Add useRadioEntropy bool, default false.

---------

Co-authored-by: Ben Meadors <benmmeadors@gmail.com>
Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>
Co-authored-by: Jonathan Bennett <jbennett@incomsystems.biz>

src/mesh/RadioLibInterface.h

@@ -172,6 +172,12 @@ class RadioLibInterface : public RadioInterface, protected concurrency::Notified
     /** Attempt to find a packet in the TxQueue. Returns true if the packet was found. */
     virtual bool findInTxQueue(NodeNum from, PacketId id) override;
 
+    /**
+     * Request randomness sourced from the LoRa modem, if supported by the active RadioLib interface.
+     * @return true if len bytes were produced, false otherwise.
+     */
+    bool randomBytes(uint8_t *buffer, size_t length);
+
   private:
     /** if we have something waiting to send, start a short (random) timer so we can come check for collision before actually
      * doing the transmit */