inference: rename refactoring for constant analysis (#44888)
The naming `ConstResult` is a bit ambiguous, given that we have several
different concepts of "constant" inference:
- constant prop': `InferenceResult`
- concrete evaluation: `ConstResult`
- WIP: semi-concrete evaluation: `SemiConcreteResult`
- (and more in the future...?)
(better to be `ConcreteResult` instead)
Now I'd like to rename `ConstResult` to `ConcreteResult` and also setup
a specific data type `ConstPropResult` representing const-prop'ed result:
- constant prop': `ConstPropResult`
- concrete evaluation: `ConcreteResult`
- WIP: semi-concrete evaluation: `SemiConcreteResult`
- (and more in the future...?)
And now `ConstResult` is a general type alias that is equivalent to
`Union{ConstPropResult,ConcreteResult,...}`.
