cmd/compile: loop induction with `*` and `<<` induction operators

```
go version go1.27-devel_a6500456f3 Wed Mar 25 22:41:27 2026 -0700 linux/amd64
```

See the following minimal repro:
```go
package p

func f(s []byte) {
for i := uint(1); i < uint(len(s)); i *= 2 {
_ = s[i]
}
}
```
This generate a bounds check even tho we don't need to.

Start by running the provided Go 1.27 development build with the minimal slice-indexing reproducer and inspect the generated code or bounds-check diagnostics. Trace the compiler's loop-induction handling for multiplication and left-shift operators; done means the unnecessary bounds check is eliminated for this case.

Written by the indexing model from the issue text.