[dlms_meter] Add dlms smart meter component (#8009)

Co-authored-by: Thomas Rupprecht <rupprecht.thomas@gmail.com>
Co-authored-by: pre-commit-ci-lite[bot] <117423508+pre-commit-ci-lite[bot]@users.noreply.github.com>
Co-authored-by: Jonathan Swoboda <154711427+swoboda1337@users.noreply.github.com>
Co-authored-by: Claude Opus 4.5 <noreply@anthropic.com>

tests/test_build_components/common/uart_2400/esp32-ard.yaml

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+# Common UART configuration for ESP32 Arduino tests - 2400 baud
+
+substitutions:
+  tx_pin: GPIO17
+  rx_pin: GPIO16
+
+uart:
+  - id: uart_bus
+    tx_pin: ${tx_pin}
+    rx_pin: ${rx_pin}
+    baud_rate: 2400

tests/test_build_components/common/uart_2400/esp32-idf.yaml

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+# Common UART configuration for ESP32 IDF tests - 2400 baud
+
+substitutions:
+  tx_pin: GPIO17
+  rx_pin: GPIO16
+
+uart:
+  - id: uart_bus
+    tx_pin: ${tx_pin}
+    rx_pin: ${rx_pin}
+    baud_rate: 2400

tests/test_build_components/common/uart_2400/esp8266-ard.yaml

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+# Common UART configuration for ESP8266 Arduino tests - 2400 baud
+
+substitutions:
+  tx_pin: GPIO4
+  rx_pin: GPIO5
+
+uart:
+  - id: uart_bus
+    tx_pin: ${tx_pin}
+    rx_pin: ${rx_pin}
+    baud_rate: 2400