Add MPR121 Capacitive Touch Sensor (#449)

* module mpr121

* added mpr121 sensor and binary sensor

* added tests

* removed CONF_CHANNELS, it is not supported in the esphome-code mpr121
code

* changed namespace for mpr121 to binary_sensor

* Update esphome/components/binary_sensor/mpr121.py

Co-Authored-By: mvturnho <qris.online@gmail.com>

* fixed class names

* fix lint errors

tests/test3.yaml

@@ -102,6 +102,10 @@ time:
 apds9960:
   address: 0x20
   update_interval: 60s
+  
+mpr121:
+  id: mpr121_first
+  address: 0x5A
 
 binary_sensor:
   - platform: apds9960
@@ -119,6 +123,23 @@ binary_sensor:
   - platform: homeassistant
     entity_id: binary_sensor.hello_world
     id: ha_hello_world_binary
+#mpr121
+  - platform: mpr121
+    id: touchkey0
+    channel: 0
+    name: "touchkey0"
+  - platform: mpr121
+    channel: 1
+    name: "touchkey1"
+  - platform: mpr121
+    channel: 2
+    name: "touchkey2"
+  - platform: mpr121
+    channel: 3
+    name: "touchkey3"
+    on_press:
+      then:
+        - switch.toggle: mpr121_toggle
 
 remote_receiver:
   pin: GPIO12
@@ -158,6 +179,12 @@ script:
     then:
       - lambda: 'ESP_LOGD("main", "Hello World!");'
 
+switch:
+  - platform: template
+    name: "mpr121_toggle"
+    id: mpr121_toggle
+    optimistic: True
+
 stepper:
   - platform: uln2003
     id: my_stepper