TCA8418 initial config + basic 3x4 keypad config (#6422)

* TCA8418 with base config for 3x4 keypad

* replaced k with uppercase K

* change detection method

* reflect changes  #6381

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Co-authored-by: Ben Meadors <benmmeadors@gmail.com>

src/main.cpp

@@ -587,6 +587,10 @@ void setup()
             // assign an arbitrary value to distinguish from other models
             kb_model = 0x37;
             break;
+        case ScanI2C::DeviceType::TCA8418KB:
+            // assign an arbitrary value to distinguish from other models
+            kb_model = 0x84;
+            break;
         default:
             // use this as default since it's also just zero
             LOG_WARN("kb_info.type is unknown(0x%02x), setting kb_model=0x00", kb_info.type);