[esp32_touch] Fix variants, add tests for variants (#8320)

tests/components/esp32_touch/common-variants.yaml

@@ -0,0 +1,15 @@
+esp32_touch:
+  setup_mode: false
+  sleep_duration: 27ms
+  measurement_duration: 8ms
+  low_voltage_reference: 0.5V
+  high_voltage_reference: 2.7V
+  voltage_attenuation: 1.5V
+
+binary_sensor:
+  - platform: esp32_touch
+    name: ESP32 Touch Pad
+    pin: ${pin}
+    threshold: 1000
+    on_press:
+      - logger.log: "I'm touched!"