Add bh1750, aht20, sgp40 drivers unified on native i2c_master API

Forked from managed_components (espressif/bh1750, espressif/aht20,
esp-idf-lib/sgp40) and rewrote aht20/sgp40 internals to use
driver/i2c_master.h directly instead of the i2c_bus and i2cdev
wrapper components, so all three sensors share one create/delete
handle pattern over a single i2c_master_bus_handle_t.

bh1750/CMakeLists.txt

@@ -0,0 +1,5 @@
+idf_component_register(
+    SRCS "bh1750.c"
+    INCLUDE_DIRS "include"
+    REQUIRES "esp_driver_i2c"
+)