This simplifies state management and the amount of terminology end-users
need to learn by using one concept `Runtime` instead of two: `Engine`
and `Store`. This bridges the concepts to the specification by still
having `wazero.Runtime` implement `wasm.Store`.
The net result is that we can know for sure which "engine" is used when
decoding. This allows us a lot of flexibility especially pre-compilation
when JIT is possible.
This also changes the default to JIT based on compiler flags so that
downstream projects like wapc-go don't have to do this individually
(including tracking of which OS+Arch have JIT).
Signed-off-by: Adrian Cole <adrian@tetrate.io>
