Consistently use device posture for auto-rotate operations

Standardizes auto-rotate settings to exclusively use device posture, removing inconsistent device state references.

Converts device state to posture at critical points and applies `DeviceStateRotationLockKey` annotations for clarity and correct usage.

Test: atest DeviceStateAutoRotateSettingControllerTests DeviceStateAutoRotateSettingManagerImplTest
Fixes: 419209239
Flag: com.android.window.flags.enable_device_state_auto_rotate_setting_refactor
Change-Id: I01dfdcd6196395fa743758ab489303cae4bb600d