[bthome] Add BTHome v2 BLE protocol support

Implements native BTHome v2 protocol support for broadcasting sensor data
over BLE advertisements. This enables ESP32 devices to act as battery-powered
BLE sensors that are natively compatible with Home Assistant.

Features:
- Support for multiple sensor types (temperature, humidity, battery, etc.)
- Support for binary sensors (motion, door, window, etc.)
- AES-CCM encryption support with 16-byte keys
- Automatic packet encoding per BTHome v2 specification
- Dynamic advertisement updates when sensor values change
- Configurable advertising intervals and TX power
- Proper BTHome v2 device info byte and service UUID

Implementation:
- Python configuration for sensor/binary sensor mapping
- C++ component for BTHome packet encoding and BLE advertising
- mbedtls CCM encryption for secure advertisements
- Leverages existing esp32_ble infrastructure

Test coverage:
- Basic sensor/binary sensor configuration tests
- Encryption test configuration
- Multi-platform support (ESP32, ESP32-C3, ESP32-S3 with IDF)

Closes: https://github.com/orgs/esphome/discussions/3235

tests/components/bthome/common.yaml

@@ -0,0 +1,32 @@
+sensor:
+  - platform: template
+    id: test_temperature
+    name: "Test Temperature"
+  - platform: template
+    id: test_humidity
+    name: "Test Humidity"
+  - platform: template
+    id: test_battery
+    name: "Test Battery"
+
+binary_sensor:
+  - platform: template
+    id: test_motion
+    name: "Test Motion"
+  - platform: template
+    id: test_door
+    name: "Test Door"
+
+bthome:
+  measurement:
+    - type: temperature
+      id: test_temperature
+    - type: humidity
+      id: test_humidity
+    - type: battery
+      id: test_battery
+  binary_sensor:
+    - type: motion
+      id: test_motion
+    - type: door
+      id: test_door

tests/components/bthome/test.esp32-c3-idf.yaml

@@ -0,0 +1 @@
+<<: !include common.yaml

tests/components/bthome/test.esp32-idf.yaml

@@ -0,0 +1 @@
+<<: !include common.yaml

tests/components/bthome/test.esp32-s3-idf.yaml

@@ -0,0 +1 @@
+<<: !include common.yaml

tests/components/bthome/test_encryption.esp32-idf.yaml

@@ -0,0 +1,18 @@
+sensor:
+  - platform: template
+    id: test_temperature
+    name: "Test Temperature"
+
+binary_sensor:
+  - platform: template
+    id: test_motion
+    name: "Test Motion"
+
+bthome:
+  encryption_key: "231d39c1d7cc1ab1aee224cd096db932"
+  measurement:
+    - type: temperature
+      id: test_temperature
+  binary_sensor:
+    - type: motion
+      id: test_motion