docs: add some (out) annotations for stream config parser functions
docs: add some (out) annotations for stream config parser functions

cablelabs/gstreamer,shelsonjava/gstreamer,jpakkane/gstreamer,lovebug356/gstreamer,krieger-od/gstreamer,cfoch/gstreamer,shelsonjava/gstreamer,ensonic/gstreamer,shelsonjava/gstreamer,ensonic/gstreamer,jpxiong/gstreamer,StreamUtils/gstreamer,jpxiong/gstreamer,justinjoy/gstreamer,jpakkane/gstreamer,centricular/gstreamer,shelsonjava/gstreamer,lovebug356/gstreamer,surround-io/gstreamer,krichter722/gstreamer,mparis/gstreamer,cablelabs/gstreamer,collects/gstreamer,krichter722/gstreamer,ensonic/gstreamer,krieger-od/gstreamer,lubosz/gstreamer,lubosz/gstreamer,StreamUtils/gstreamer,centricular/gstreamer,collects/gstreamer,lovebug356/gstreamer,cfoch/gstreamer,ensonic/gstreamer,StreamUtils/gstreamer,surround-io/gstreamer,centricular/gstreamer,jpxiong/gstreamer,krichter722/gstreamer,jpxiong/gstreamer,mparis/gstreamer,Lachann/gstreamer,cfoch/gstreamer,justinjoy/gstreamer,jpxiong/gstreamer,collects/gstreamer,jpakkane/gstreamer,Lachann/gstreamer,cfoch/gstreamer,Lachann/gstreamer,jpakkane/gstreamer,mparis/gstreamer,shelsonjava/gstreamer,mparis/gstreamer,centricular/gstreamer,lovebug356/gstreamer,Lachann/gstreamer,StreamUtils/gstreamer,surround-io/gstreamer,mparis/gstreamer,cablelabs/gstreamer,justinjoy/gstreamer,surround-io/gstreamer,lubosz/gstreamer,lubosz/gstreamer,cfoch/gstreamer,Lachann/gstreamer,jpakkane/gstreamer,collects/gstreamer,surround-io/gstreamer,krichter722/gstreamer,collects/gstreamer,justinjoy/gstreamer,centricular/gstreamer,krieger-od/gstreamer,justinjoy/gstreamer,krichter722/gstreamer,cablelabs/gstreamer,lubosz/gstreamer,lovebug356/gstreamer,krieger-od/gstreamer,ensonic/gstreamer,StreamUtils/gstreamer,cablelabs/gstreamer,krieger-od/gstreamer