Mark hal_camera_default as a client of hal_graphics_allocator

Address the denials:
avc:  denied  { find } for interface=android.hardware.graphics.mapper::IMapper
sid=u:r:hal_camera_default:s0 pid=1400 scontext=u:r:hal_camera_default:s0
tcontext=u:object_r:hal_graphics_mapper_hwservice:s0 tclass=hwservice_manager
permissive=1

avc: denied { read } for
path=2F6465762F6173686D656D2F6772616C6C6F632D313430382E3536202864656C6574656429
dev="tmpfs" ino=21847 scontext=u:r:hal_camera_default:s0
tcontext=u:object_r:hal_graphics_allocator_default_tmpfs:s0 tclass=file
permissive=1

This change attaches hal_graphics_allocator_client attribute to
hal_camera_default. hal_graphics_allocator_client has above permissions from:
https://android.googlesource.com/platform/system/sepolicy/+/master/public/hal_graphics_allocator.te#5
https://android.googlesource.com/device/google/cuttlefish/+/refs/heads/master-cuttlefish-testing/shared/sepolicy/hal_graphics_allocator.te#2

Bug: 28053261
Test: start camera, take a picture
Change-Id: I435c955e1b1e0ef913aa499cf560561a86202dcb