[clang] [Clang] Implement P2718R0 "Lifetime extension in range-based for loops" (PR #76361)

[Aaron Ballman via cfe-commits]

https://github.com/AaronBallman commented:

Thank you for this! I think it looks pretty close, but I'd love to get more eyes on this given the importance of the feature. CC @zygoloid @rjmccall @erichkeane 

https://github.com/llvm/llvm-project/pull/76361