registry: Cache element and typefind factories. Fixes 598896
registry: Cache element and typefind factories. Fixes 598896

This avoids unneeded list/filtering if the registry hasn't changed

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