auto merge of #19569 : murphm8/rust/ring_buf_insert, r=Gankro
auto merge of #19569 : murphm8/rust/ring_buf_insert, r=Gankro

This is a first pass at insert on RingBuf. I tried to keep it as simple as possible. I'm not sure of the performance implications of doing one copy vs. copying multiple times but moving a smaller amount of memory. I chose to stick with one copy, even if the amount of memory I have to move is larger.

I believe this is part of #18424 

@Gankro mentioned this was missing.

bombless/rust-docs-chinese,robertg/rust,pelmers/rust,ktossell/rust,zubron/rust,aidancully/rust,sae-bom/rust,victorvde/rust,mihneadb/rust,AerialX/rust-rt-minimal,reem/rust,andars/rust,mdinger/rust,seanrivera/rust,kimroen/rust,hauleth/rust,miniupnp/rust,pshc/rust,rprichard/rust,jroesch/rust,ejjeong/rust,ebfull/rust,rprichard/rust,vhbit/rust,defuz/rust,rohitjoshi/rust,mahkoh/rust,bombless/rust,rohitjoshi/rust,ebfull/rust,mihneadb/rust,mahkoh/rust,kwantam/rust,TheNeikos/rust,zaeleus/rust,jashank/rust,pelmers/rust,ktossell/rust,TheNeikos/rust,pshc/rust,AerialX/rust-rt-minimal,nwin/rust,ejjeong/rust,zachwick/rust,ejjeong/rust,philyoon/rust,mvdnes/rust,vhbit/rust,aepsil0n/rust,l0kod/rust,mvdnes/rust,GBGamer/rust,ruud-v-a/rust,mvdnes/rust,AerialX/rust-rt-minimal,vhbit/rust,jashank/rust,ebfull/rust,defuz/rust,ktossell/rust,aepsil0n/rust,kwantam/rust,dinfuehr/rust,rohitjoshi/rust,robertg/rust,sae-bom/rust,rohitjoshi/rust,mahkoh/rust,KokaKiwi/rust,jroesch/rust,avdi/rust,philyoon/rust,philyoon/rust,hauleth/rust,dinfuehr/rust,richo/rust,aneeshusa/rust,kwantam/rust,bombless/rust,defuz/rust,aepsil0n/rust,dwillmer/rust,bombless/rust,jroesch/rust,rprichard/rust,GBGamer/rust,victorvde/rust,kimroen/rust,avdi/rust,krzysz00/rust,vhbit/rust,kwantam/rust,AerialX/rust,vhbit/rust,dwillmer/rust,miniupnp/rust,cllns/rust,TheNeikos/rust,ruud-v-a/rust,aidancully/rust,victorvde/rust,KokaKiwi/rust,aidancully/rust,aneeshusa/rust,nwin/rust,rohitjoshi/rust,dwillmer/rust,rprichard/rust,zubron/rust,zaeleus/rust,TheNeikos/rust,zachwick/rust,reem/rust,pelmers/rust,rohitjoshi/rust,reem/rust,bombless/rust,rprichard/rust,sae-bom/rust,mdinger/rust,mvdnes/rust,philyoon/rust,hauleth/rust,richo/rust,AerialX/rust,avdi/rust,XMPPwocky/rust,GBGamer/rust,mdinger/rust,miniupnp/rust,gifnksm/rust,hauleth/rust,dwillmer/rust,AerialX/rust,zubron/rust,ktossell/rust,andars/rust,seanrivera/rust,nwin/rust,jroesch/rust,GBGamer/rust,krzysz00/rust,ruud-v-a/rust,zachwick/rust,GBGamer/rust,graydon/rust,jroesch/rust,sae-bom/rust,mdinger/rust,krzysz00/rust,carols10cents/rust,victorvde/rust,l0kod/rust,carols10cents/rust,kimroen/rust,reem/rust,cllns/rust,andars/rust,richo/rust,zubron/rust,krzysz00/rust,jroesch/rust,sae-bom/rust,mdinger/rust,mvdnes/rust,aepsil0n/rust,zaeleus/rust,zubron/rust,zachwick/rust,miniupnp/rust,philyoon/rust,vhbit/rust,GBGamer/rust,cllns/rust,aidancully/rust,zaeleus/rust,zachwick/rust,nwin/rust,nwin/rust,l0kod/rust,dinfuehr/rust,cllns/rust,jashank/rust,untitaker/rust,aidancully/rust,gifnksm/rust,seanrivera/rust,jashank/rust,cllns/rust,nwin/rust,nwin/rust,AerialX/rust,gifnksm/rust,mahkoh/rust,kwantam/rust,pshc/rust,bombless/rust,untitaker/rust,untitaker/rust,aneeshusa/rust,defuz/rust,jashank/rust,dwillmer/rust,XMPPwocky/rust,XMPPwocky/rust,mihneadb/rust,jashank/rust,richo/rust,omasanori/rust,gifnksm/rust,vhbit/rust,pshc/rust,mdinger/rust,miniupnp/rust,pshc/rust,ebfull/rust,robertg/rust,zaeleus/rust,aepsil0n/rust,graydon/rust,dwillmer/rust,zaeleus/rust,dinfuehr/rust,hauleth/rust,reem/rust,pelmers/rust,GBGamer/rust,ebfull/rust,andars/rust,seanrivera/rust,graydon/rust,omasanori/rust,richo/rust,ktossell/rust,aidancully/rust,omasanori/rust,aneeshusa/rust,ruud-v-a/rust,seanrivera/rust,KokaKiwi/rust,omasanori/rust,carols10cents/rust,ejjeong/rust,zachwick/rust,GBGamer/rust,kimroen/rust,KokaKiwi/rust,defuz/rust,kimroen/rust,miniupnp/rust,victorvde/rust,jroesch/rust,dinfuehr/rust,robertg/rust,ebfull/rust,dwillmer/rust,graydon/rust,cllns/rust,vhbit/rust,robertg/rust,pshc/rust,zubron/rust,kimroen/rust,l0kod/rust,bombless/rust,dwillmer/rust,hauleth/rust,kimroen/rust,l0kod/rust,AerialX/rust,AerialX/rust,seanrivera/rust,krzysz00/rust,pelmers/rust,mahkoh/rust,ruud-v-a/rust,l0kod/rust,TheNeikos/rust,victorvde/rust,XMPPwocky/rust,avdi/rust,carols10cents/rust,AerialX/rust-rt-minimal,KokaKiwi/rust,kwantam/rust,jashank/rust,mihneadb/rust,krzysz00/rust,sae-bom/rust,untitaker/rust,TheNeikos/rust,KokaKiwi/rust,untitaker/rust,dinfuehr/rust,avdi/rust,ruud-v-a/rust,zubron/rust,carols10cents/rust,richo/rust,mahkoh/rust,untitaker/rust,omasanori/rust,aneeshusa/rust,rprichard/rust,andars/rust,avdi/rust,miniupnp/rust,nwin/rust,defuz/rust,XMPPwocky/rust,l0kod/rust,philyoon/rust,gifnksm/rust,graydon/rust,pshc/rust,mvdnes/rust,mihneadb/rust,miniupnp/rust,jroesch/rust,ejjeong/rust,omasanori/rust,AerialX/rust-rt-minimal,andars/rust,XMPPwocky/rust,aneeshusa/rust,jashank/rust,ktossell/rust,AerialX/rust-rt-minimal,graydon/rust,zubron/rust,reem/rust,ktossell/rust,carols10cents/rust,pshc/rust,pelmers/rust,mihneadb/rust,ejjeong/rust,aepsil0n/rust,l0kod/rust,gifnksm/rust,robertg/rust