utils: codegen: ipc: Split proxy types

Even though there is an abstract class to represent the interface of an IPA,
the threaded and IPC versions are still multiplexed using the same type,
which uses a boolean to actually dispatch to the right function.

Instead of doing that, split the classes into "threaded" and "isolated"
variants, and make `IPAManager` choose accordingly.

Signed-off-by: Barnabás Pőcze <barnabas.pocze@ideasonboard.com>
Reviewed-by: Paul Elder <paul.elder@ideasonboard.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>

include/libcamera/internal/ipa_manager.h

@@ -44,7 +44,14 @@ public:
 			return nullptr;
 
 		const GlobalConfiguration &configuration = cm->_d()->configuration();
-		std::unique_ptr<T> proxy = std::make_unique<T>(m, !self->isSignatureValid(m), configuration);
+
+		auto proxy = [&]() -> std::unique_ptr<T> {
+			if (self->isSignatureValid(m))
+				return std::make_unique<typename T::Threaded>(m, configuration);
+			else
+				return std::make_unique<typename T::Isolated>(m, configuration);
+		}();
+
 		if (!proxy->isValid()) {
 			LOG(IPAManager, Error) << "Failed to load proxy";
 			return nullptr;