[llvm] [llvm][ARM]Add ARM widen strings pass (PR #107120)

[Eli Friedman via llvm-commits]

https://github.com/efriedma-quic commented:

Probably worth investigating if we can fit this easily into some pass that's already examining the uses of globals, like GlobalOpt; iterating over the whole module isn't cheap.

https://github.com/llvm/llvm-project/pull/107120