Add input_device.config_file.apex property

This new property is to set an apex name when input configuration files
are bundled in an apex.

libinput checks the new sysprop when loading input configuration.

This removes hard-coded apex name (com.android.input.config).

Bug: 315080500
Test: adb shell dumpsys input
  # set "touch.orientationAware = 0" in Touchscreen_0.idc
  # build/install the input config apex
  # Observe the Input configuration
  # "Touch Input Mapper" shows "OrientationAware: false"
Change-Id: Ie0bf30bff2ed7f983caa5b893994a5bd2759e192
diff --git a/private/property_contexts b/private/property_contexts
index fe12202..7e31dd7 100644
--- a/private/property_contexts
+++ b/private/property_contexts
@@ -288,6 +288,9 @@
 persist.device_config.memory_safety_native.         u:object_r:device_config_memory_safety_native_prop:s0
 persist.device_config.tethering_u_or_later_native.  u:object_r:device_config_tethering_u_or_later_native_prop:s0
 
+# Prop indicates the apex that bundles input configuration files (*.idc,*.kl,*.kcm)
+input_device.config_file.apex    u:object_r:input_device_config_prop:s0 exact string
+
 # Properties that is for staging
 next_boot.  u:object_r:next_boot_prop:s0