media: Consolidates and implements XML based config reading

Consolidates system/session properties into platform specific configs
which can be parsed during media codec process start and the property
values can be used during component initialization. This can also be
used to switch properties between video sessions - based on PL/test-
scenario requirements by making modifications to the config file and
"restarting" media codec process

Change-Id: Ia16accec5716b2337722c1e2e276702c75775d75
CRs-Fixed: 2066348

• Android.mk[diff]
• conf_files/sdm845/sdm845.mk[Added - diff]
• conf_files/sdm845/system_properties.xml[Added - diff]
• libplatformconfig/Android.mk[Added - diff]
• libplatformconfig/ConfigParser.cpp[Added - diff]
• libplatformconfig/ConfigParser.h[Added - diff]
• libplatformconfig/PlatformConfig.cpp[Added - diff]
• libplatformconfig/PlatformConfig.h[Added - diff]
• mm-core/Android.mk[diff]
• mm-video-v4l2/vidc/vdec/Android.mk[diff]
• mm-video-v4l2/vidc/vdec/src/omx_vdec_v4l2.cpp[diff]
• mm-video-v4l2/vidc/venc/Android.mk[diff]
• mm-video-v4l2/vidc/venc/src/omx_swvenc_mpeg4.cpp[diff]
• mm-video-v4l2/vidc/venc/src/video_encoder_device_v4l2.cpp[diff]