[llvm] A MMIWP Constructor Initialized with the move constructor of MMI (PR #98770)

[Matt Arsenault via llvm-commits]

arsenm wrote:

> > Yes, the machine function map gets moved; but each machine function holds an internal reference to the original MMI and its context, and moving them makes those references stale.
> 
> Can we remove this reference from MachineFunction? Intuitively it shouldn't be necessary. A quick grep shows limited uses, and in contexts where it should be directly queryable from the PM

https://github.com/llvm/llvm-project/pull/99652 starts moving towards this 

https://github.com/llvm/llvm-project/pull/98770