Decouple ViewEngine from compiler

[rexm]

There are a few places (such as the PartialBinder) where the compiler itself is tightly coupled to the ViewEngine construct.

It would be ideal to have the ViewEngine abstracted behind the Configuration/Context. This may require significant breaking changes, so it would be targeted for v2.

[rexm]

On the 2.0 roadmap.

[rexm]

This remains a valid long-term goal but requires significant breaking changes. Deferring to a future major version. Keeping open as a milestone marker.