Add checking signature process for "XR_EXTX_OVERLAY_EXTENSION_NAME"

Purpose

To increase security of AIDL interfaces of overlay service, add checking signature process for "XR_EXTX_OVERLAY_EXTENSION_NAME".

Design

Changes

1. Check android signature for "XR_EXTX_OVERLAY_EXTENSION_NAME" when overlay service app calls "xrCreateInstance()".
2. Add system property "debug.openxr.runtime.checkOverlaySignature" to control this feature.
3. Using "XRT_ANDROID_PACKAGE" which is set in cmake file to get runtime/spaces package name.

Verification

Prepare:

1. monado: packed with signature, outOfProcess.
2. hello_xr app: packed with signature, add "XR_EXTX_OVERLAY_EXTENSION_NAME" extension.

Test cases:

1. setprop debug.openxr.runtime.checkOverlaySignature true

case	result
monado + hello_xr app(with same signature)	hello_xr can work
monado + hello_xr app(with different signatures)	hello_xr cannot work

2. setprop debug.openxr.runtime.checkOverlaySignature false

case	result
monado + hello_xr app(with same signature)	hello_xr can work
monado + hello_xr app(with different signatures)	hello_xr can work

Other Impact

Once enable this feature, all apps using "XR_EXTX_OVERLAY_EXTENSION_NAME" will have to be signed with the same signature of "XRT_ANDROID_PACKAGE".