This commit replaces the `IncrementalDriver` abstraction which powered
incremental compilation in the compiler with a new `IncrementalCompilation`
design. Principally, it separates two concerns which were tied together in
the previous implementation:
1. Tracking the reusable state of a compilation at any given point that
could be reused in a subsequent future compilation.
2. Making use of a prior compilation's state to accelerate the current one.
The new abstraction adds explicit tracking and types to deal with both of
these concerns separately, which greatly reduces the complexity of the state
tracking that `IncrementalDriver` used to perform.
PR Close#41475
94ec0af582