Perform instsimplify before inline to eliminate some trivial calls
I am currently working on #128081. In the current pipeline, we can get the following clone statements ([godbolt](https://rust.godbolt.org/z/931316fhP)):
```
bb0: {
StorageLive(_2);
_2 = ((*_1).0: i32);
StorageLive(_3);
_3 = ((*_1).1: u64);
_0 = Foo { a: move _2, b: move _3 };
StorageDead(_3);
StorageDead(_2);
return;
}
```
Analyzing such statements will be simple and fast. We don't need to consider branches or some interfering statements. However, this requires us to run `InstSimplify`, `ReferencePropagation`, and `SimplifyCFG` at least once. I can introduce a new pass, but I think the best place for it would be within `InstSimplify`.
I put `InstSimplify` before `Inline`, which takes some of the burden away from `Inline`.
r? `@saethlin`
4db3d12e6f