parse-launch: allow specifying GstElement properties via gst_parse_bin_from_description
parse-launch: allow specifying GstElement properties via gst_parse_bin_from_description

If deserializing a property fails, check if the value type is a string and if so
attempt to create a bin from the string value. This allows to e.g. specify
audio-sink/video-sink for playbin on gst-launch commandline.

jpakkane/gstreamer,cablelabs/gstreamer,krieger-od/gstreamer,ahmedammar/platform_external_gst_gstreamer,mrchapp/gstreamer,mrchapp/gstreamer,surround-io/gstreamer,krieger-od/gstreamer,mparis/gstreamer,ensonic/gstreamer,drothlis/gstreamer,justinjoy/gstreamer,cablelabs/gstreamer,shelsonjava/gstreamer,surround-io/gstreamer,surround-io/gstreamer,ylatuya/gstreamer,collects/gstreamer,lubosz/gstreamer,cfoch/gstreamer,krieger-od/gstreamer,krieger-od/gstreamer,surround-io/gstreamer,centricular/gstreamer,jpxiong/gstreamer,ahmedammar/platform_external_gst_gstreamer,cfoch/gstreamer,jpakkane/gstreamer,ylatuya/gstreamer,cablelabs/gstreamer,ensonic/gstreamer,StreamUtils/gstreamer,mrchapp/gstreamer,cfoch/gstreamer,drothlis/gstreamer,StreamUtils/gstreamer,Distrotech/gstreamer,jpakkane/gstreamer,lovebug356/gstreamer,mparis/gstreamer,StreamUtils/gstreamer,magcius/gstreamer,collects/gstreamer,ensonic/gstreamer,lovebug356/gstreamer,cablelabs/gstreamer,lubosz/gstreamer,ahmedammar/platform_external_gst_gstreamer,surround-io/gstreamer,Distrotech/gstreamer,ensonic/gstreamer,centricular/gstreamer,shelsonjava/gstreamer,drothlis/gstreamer,mparis/gstreamer,lovebug356/gstreamer,shelsonjava/gstreamer,jpxiong/gstreamer,ahmedammar/platform_external_gst_gstreamer,centricular/gstreamer,jpakkane/gstreamer,Lachann/gstreamer,ylatuya/gstreamer,Distrotech/gstreamer,krichter722/gstreamer,justinjoy/gstreamer,centricular/gstreamer,justinjoy/gstreamer,lovebug356/gstreamer,ensonic/gstreamer,ylatuya/gstreamer,jpxiong/gstreamer,lubosz/gstreamer,cfoch/gstreamer,ylatuya/gstreamer,drothlis/gstreamer,Distrotech/gstreamer,Distrotech/gstreamer,mparis/gstreamer,collects/gstreamer,jpakkane/gstreamer,magcius/gstreamer,cablelabs/gstreamer,cfoch/gstreamer,Lachann/gstreamer,lubosz/gstreamer,justinjoy/gstreamer,Lachann/gstreamer,Lachann/gstreamer,magcius/gstreamer,magcius/gstreamer,shelsonjava/gstreamer,collects/gstreamer,mparis/gstreamer,Lachann/gstreamer,StreamUtils/gstreamer,drothlis/gstreamer,krichter722/gstreamer,ahmedammar/platform_external_gst_gstreamer,krieger-od/gstreamer,magcius/gstreamer,lubosz/gstreamer,krichter722/gstreamer,justinjoy/gstreamer,jpxiong/gstreamer,mrchapp/gstreamer,centricular/gstreamer,krichter722/gstreamer,collects/gstreamer,krichter722/gstreamer,mrchapp/gstreamer,StreamUtils/gstreamer,jpxiong/gstreamer,lovebug356/gstreamer,shelsonjava/gstreamer