Support drm hwcomposer as an apex

... so that Cuttlefish can runtime select between drm_hwcomposer
and ranchu.

Drops the libbinder to avoid error:

  APEX can't use libbinder (must use libbinder_ndk)

and fixes a couple includes.

Bug: b/348466630
Test: cvd start
Test: cvd start --hwcomposer=drm_hwcomposer
Change-Id: I50681677d89c56fb6761b740a465bf92890157ea
diff --git a/hwc3/hwc3-apex-file-contexts b/hwc3/hwc3-apex-file-contexts
new file mode 100644
index 0000000..5c8de15
--- /dev/null
+++ b/hwc3/hwc3-apex-file-contexts
@@ -0,0 +1,3 @@
+(/.*)?                                                   u:object_r:vendor_file:s0
+/etc(/.*)?                                               u:object_r:vendor_configs_file:s0
+/bin/hw/android\.hardware\.composer\.hwc3-service\.drm   u:object_r:hal_graphics_composer_default_exec:s0
\ No newline at end of file