[String] [Foundation] perf: UTF8 String -> Data
[String] [Foundation] perf: UTF8 String -> Data

Currently, `str.data(using:allowLossyConversion)` always bridges via
`NSString`.

As `String` is now natively UTF8 we can fastpath this conversion in the
case where the user requests UTF8 encoding.

A benchmark for this was previously added in #22648.

jckarter/swift,airspeedswift/swift,ahoppen/swift,allevato/swift,parkera/swift,shahmishal/swift,allevato/swift,xedin/swift,roambotics/swift,ahoppen/swift,apple/swift,devincoughlin/swift,shahmishal/swift,shahmishal/swift,roambotics/swift,rudkx/swift,gregomni/swift,JGiola/swift,karwa/swift,glessard/swift,CodaFi/swift,airspeedswift/swift,hooman/swift,parkera/swift,lorentey/swift,parkera/swift,nathawes/swift,stephentyrone/swift,ahoppen/swift,hooman/swift,harlanhaskins/swift,benlangmuir/swift,lorentey/swift,CodaFi/swift,devincoughlin/swift,apple/swift,aschwaighofer/swift,xwu/swift,lorentey/swift,shahmishal/swift,shajrawi/swift,allevato/swift,JGiola/swift,gribozavr/swift,devincoughlin/swift,rudkx/swift,tkremenek/swift,allevato/swift,gregomni/swift,benlangmuir/swift,jmgc/swift,gribozavr/swift,karwa/swift,ahoppen/swift,tkremenek/swift,JGiola/swift,airspeedswift/swift,xedin/swift,sschiau/swift,apple/swift,xwu/swift,gribozavr/swift,aschwaighofer/swift,harlanhaskins/swift,stephentyrone/swift,sschiau/swift,karwa/swift,gribozavr/swift,hooman/swift,xwu/swift,aschwaighofer/swift,stephentyrone/swift,xedin/swift,aschwaighofer/swift,rudkx/swift,shahmishal/swift,xwu/swift,tkremenek/swift,devincoughlin/swift,jckarter/swift,gregomni/swift,nathawes/swift,airspeedswift/swift,devincoughlin/swift,hooman/swift,sschiau/swift,parkera/swift,CodaFi/swift,glessard/swift,nathawes/swift,aschwaighofer/swift,atrick/swift,karwa/swift,parkera/swift,jmgc/swift,sschiau/swift,hooman/swift,ahoppen/swift,tkremenek/swift,atrick/swift,roambotics/swift,rudkx/swift,devincoughlin/swift,jmgc/swift,glessard/swift,jmgc/swift,shahmishal/swift,sschiau/swift,CodaFi/swift,shajrawi/swift,stephentyrone/swift,parkera/swift,karwa/swift,gregomni/swift,tkremenek/swift,tkremenek/swift,shajrawi/swift,hooman/swift,glessard/swift,atrick/swift,allevato/swift,shajrawi/swift,JGiola/swift,devincoughlin/swift,harlanhaskins/swift,atrick/swift,sschiau/swift,lorentey/swift,harlanhaskins/swift,glessard/swift,JGiola/swift,allevato/swift,gregomni/swift,shajrawi/swift,rudkx/swift,devincoughlin/swift,shajrawi/swift,parkera/swift,xedin/swift,karwa/swift,benlangmuir/swift,benlangmuir/swift,hooman/swift,xwu/swift,gribozavr/swift,gribozavr/swift,nathawes/swift,harlanhaskins/swift,lorentey/swift,shahmishal/swift,CodaFi/swift,jckarter/swift,benlangmuir/swift,gregomni/swift,glessard/swift,shajrawi/swift,jmgc/swift,xwu/swift,stephentyrone/swift,roambotics/swift,aschwaighofer/swift,karwa/swift,atrick/swift,jckarter/swift,nathawes/swift,xedin/swift,roambotics/swift,apple/swift,shajrawi/swift,JGiola/swift,aschwaighofer/swift,ahoppen/swift,airspeedswift/swift,allevato/swift,apple/swift,harlanhaskins/swift,nathawes/swift,airspeedswift/swift,airspeedswift/swift,stephentyrone/swift,lorentey/swift,atrick/swift,shahmishal/swift,stephentyrone/swift,sschiau/swift,jckarter/swift,jckarter/swift,gribozavr/swift,parkera/swift,lorentey/swift,CodaFi/swift,xedin/swift,xedin/swift,jckarter/swift,jmgc/swift,sschiau/swift,harlanhaskins/swift,benlangmuir/swift,nathawes/swift,rudkx/swift,lorentey/swift,tkremenek/swift,roambotics/swift,gribozavr/swift,xwu/swift,karwa/swift,xedin/swift,jmgc/swift,CodaFi/swift,apple/swift