Emit a 'known devices changed' event when we forget a known device

Makes the Lua UI update immediately after running the bt_forget command
added in PR #289

src/drivers/bluetooth.cpp

@@ -188,6 +188,8 @@ auto Bluetooth::knownDevices() -> std::vector<bluetooth::MacAndName> {
 
 auto Bluetooth::forgetKnownDevice(const bluetooth::mac_addr_t& mac) -> void {
   nvs_.BluetoothName(mac, {});
+  std::invoke(bluetooth::BluetoothState::eventHandler(),
+              bluetooth::SimpleEvent::kKnownDevicesChanged);
 }
 
 auto Bluetooth::discoveryEnabled(bool en) -> void {
@@ -414,6 +416,10 @@ auto BluetoothState::pairedDevice(std::optional<MacAndName> dev) -> void {
       bluetooth::events::PairedDeviceChanged{});
 }
 
+auto BluetoothState::eventHandler() -> std::function<void(Event)>& {
+  return sEventHandler_;
+}
+
 auto BluetoothState::discovery() -> bool {
   return sScanner_->enabled();
 }

src/drivers/include/drivers/bluetooth.hpp

@@ -162,6 +162,8 @@ class BluetoothState : public tinyfsm::Fsm<BluetoothState> {
   static auto pairedDevice() -> std::optional<bluetooth::MacAndName>;
   static auto pairedDevice(std::optional<bluetooth::MacAndName>) -> void;
 
+  static auto eventHandler() -> std::function<void(Event)>&;
+
   static auto discovery() -> bool;
   static auto discovery(bool) -> void;
   static auto discoveredDevices() -> std::vector<Device>;