Built on top of #41882, this PR sorts out the constant-prop' interface
yet more, particularly generalizes `force_const_prop` to `const_prop_config`
so that it can turn on and off each heuristic.

The main motivation here is, in #41882, we want to force const-prop' on
`setproperty` even when its return type is already `Const` for the sake
of succeeding inlining, by skipping all the `const_prop_xxx_heuristic` checks.
But I still found we want to apply `const_prop_entry_heuristic` to
`getproperty`, because if we already know very accurate result for a
`getproperty` call, usually there is really no motivation for constant-prop', e.g.:
```julia
struct FZero end
Base.getproperty(::FZero, ::Symbol) = 0.0
getproperty(FZero(), :val) # const-prop' doesn't need to happen here
```

Now `force_const_prop(...) -> force::Bool` is refactored to
`const_prop_config(...) -> config::UInt8`, which can turn on and off
each heuristic based on the value of `config`.

I also included another refactoring that inlines `const_prop_rettype_heuristic`
into `const_prop_argument_heuristic`, because they really seem tightly coupled.