This removes an unnecessary coupling between ExecutorProcessControl and
DylibManager, allowing clients to select DylibManager implementations
independently.
To simplify the transition, the
ExecutorProcessControl::createDefaultJITDylib method will return an
instance of whatever DylibManager the ExecutorProcessControl
implementation had been using previously.
This patch adds the new **executor-side resolver API** as suggested by
@lhames. It introduces a `DylibSymbolResolver` that helps resolve
symbols for each loaded dylib.
Previously, we returned a `DylibHandle` to the controller. Now, we wrap
the native handle inside `DylibSymbolResolver` and return a
`ResolverHandle` instead. This makes the code cleaner and separates the
symbol resolution logic from raw handle management.
