[ownership] Give better names to methods on OwnershipLifetimeExtender.
[ownership] Give better names to methods on OwnershipLifetimeExtender.

Specifically,

copyAndExtendForLifetimeEndingRAUW -> createPlusOneCopy(value, oldConsumingUse)
copyAndExtendForNonLifetimeEndingRAUW -> createPlusZeroCopy(value, nonLifetimeEndingUses)
copyBorrowAndExtendForRAUW -> createPlusZeroBorrow(value, nonLifetimeEndingUses)

Beyond being shorter, the PlusOne vs PlusZero mnemonic is telling the caller
whether or not the caller is responsible for cleaning up the returned
copy_value. In the PlusZero cases, we assume that all uses are non-lifetime
ending and we need to insert all destroy_value at the liveness points of the
value.

In the PlusOne case in contrast, we are supposed to make a copy of value and the
complete oldConsumingUse's block into a joint post-dominance set of blocks. Then
we insert destroy_values for our new copy into the completion blocks that we
found and leave cleaning up value along paths through oldConsumingUse to our
user. In this sense the value is a PlusOne value that our user must clean up for
us (sorta makes me think about ManagedValue).

xwu/swift,ahoppen/swift,tkremenek/swift,parkera/swift,gregomni/swift,parkera/swift,hooman/swift,ahoppen/swift,apple/swift,glessard/swift,roambotics/swift,xwu/swift,tkremenek/swift,parkera/swift,hooman/swift,gregomni/swift,benlangmuir/swift,apple/swift,JGiola/swift,benlangmuir/swift,roambotics/swift,roambotics/swift,hooman/swift,tkremenek/swift,tkremenek/swift,parkera/swift,atrick/swift,atrick/swift,apple/swift,roambotics/swift,JGiola/swift,gregomni/swift,ahoppen/swift,ahoppen/swift,tkremenek/swift,parkera/swift,gregomni/swift,benlangmuir/swift,JGiola/swift,rudkx/swift,glessard/swift,xwu/swift,glessard/swift,JGiola/swift,rudkx/swift,hooman/swift,ahoppen/swift,glessard/swift,apple/swift,benlangmuir/swift,atrick/swift,roambotics/swift,atrick/swift,hooman/swift,hooman/swift,JGiola/swift,rudkx/swift,xwu/swift,atrick/swift,parkera/swift,tkremenek/swift,glessard/swift,rudkx/swift,xwu/swift,glessard/swift,parkera/swift,hooman/swift,apple/swift,benlangmuir/swift,gregomni/swift,atrick/swift,rudkx/swift,xwu/swift,ahoppen/swift,xwu/swift,tkremenek/swift,gregomni/swift,rudkx/swift,JGiola/swift,roambotics/swift,parkera/swift,benlangmuir/swift,apple/swift