ohos: port qtsensors plugin from qt5

Introduce a Qt Sensors backend plugin for OHOS. The plugin registers
available OHOS sensor types with QSensorManager and maps them to the
corresponding Qt sensor types.

Add backend implementations for accelerometer, gyroscope, light,
magnetometer, and rotation sensors. The OHOS sensor manager handles
sensor discovery, capability queries, subscription lifecycle, event
callbacks, and delivery of readings back to the Qt thread.

Task-number: QTBUG-146844
Pick-to: 6.12
Change-Id: I10921146321a17f678a0e400bfa214887ba6f68e
Reviewed-by: Dawid Śliwa <dawid.sliwa@qt.io>
Reviewed-by: Joerg Bornemann <joerg.bornemann@qt.io>
Reviewed-by: Zbigniew Chyla <zbigniew.chyla@qt.io>
Reviewed-by: Liang Qi <liang.qi@qt.io>