Function resolveControlStrategy

Resolves which RemoteBrowserControlStrategy the engine should use for a backend, honoring an optional caller preference.

Precedence (highest to lowest):

1. NativeAI — chosen only when the backend advertises NativeAIControl and the caller did not explicitly pin ComputerUse. (A caller preference of 'NativeAI' is honored only if the backend actually supports it; an explicit 'ComputerUse' always suppresses native delegation.)
2. ComputerUse — the universal default, chosen whenever the backend exposes the RawCdpControl substrate and native control was not selected above.
3. ComputerUse — also the fallback when neither flag is set, because CDP-connect is the one primitive every backend is expected to provide; emitting ComputerUse lets the caller surface a clear downstream error if the backend genuinely cannot be driven, rather than this helper inventing an unsupported strategy.