Add option to disable dedicated Universal architecture picker and use Container Browser

Add the ui.files.universal.dedicatedPicker setting, allowing users to choose
between the dedicated architecture picker dialog and the standard container
browser for opening Universal (fat) Mach-O binaries. Previously the dedicated
picker was always used with no way to opt out.

Implementing this required restructuring how Universal binaries are handled
during file open. The previous approach intercepted Universal binaries during
container processing, bypassing the container browser's normal pipeline with
dedicated routing logic. This tightly coupled Universal-specific behavior into
the container system, prevented the container browser from handling Universal
binaries natively, and introduced several bugs around exclusion settings,
nested containers, and multi-child container hierarchies.

Bug fixes:
- The previous implementation always intercepted Universal binaries during
  container processing with its own routing logic, bypassing the container
  browser entirely. There was no way for the container browser to handle
  Universal binaries natively, even when that was the desired behavior.
- Universal binaries inside multi-child containers were not detected. The
  previous implementation only traversed single-child paths in the container
  hierarchy, silently ignoring Universal binaries that appeared as siblings
  among multiple children.
- Nested containers (e.g., archives) inside Universal slices were not
  handled. The previous implementation intercepted Universal binaries at the
  transform routing level before the container browser could perform
  recursive delayering. When the dedicated picker is disabled, the container
  browser now processes the full hierarchy including Universal slices and any
  containers within them.
- Reverted incorrect IsInteractive to IsUIEnabled change in
  UniversalTransform. The previous change conflated headless mode with
  non-interactive processing. The UI can be enabled while still performing a
  non-interactive auto-open (e.g., container browser auto-resolving with a
  preferred architecture). The IsInteractive() flag captures the actual
  intent and enables the transform to produce only the preferred
  architecture child for non-interactive sessions, avoiding unnecessary
  BinaryView construction for all slices.

Author: bpotchik

ui/containerbrowser.h

@@ -15,7 +15,6 @@
 
 #include <vector>
 
-class ContainerOpenRequest;
 
 class ContainerTreeModel : public QAbstractItemModel
 {
@@ -122,8 +121,4 @@ class BINARYNINJAUIAPI ContainerBrowser : public QDialog
 	bool openWithOptionsRequested() const { return m_openWithOptionsRequested; }
 
 	static std::vector<TransformContextRef> openContainerFile(const QString& path, bool forceShowDialog = false, bool* outOpenWithOptions = nullptr);
-
-	// Show the container browser dialog for the given open request.
-	// Returns the selected contexts, or empty if the user cancelled.
-	static std::vector<TransformContextRef> showBrowser(ContainerOpenRequest& request, bool* outOpenWithOptions = nullptr);
 };

ui/containeropenrequest.h

@@ -266,20 +266,19 @@ bool UniversalTransform::DecodeWithContext(Ref<TransformContext> context, const
 			architectures.push_back(archName);
 		}
 
-		// TODO: It is surprising that this is UniversalTransform's responsibility.
-		if (!BinaryNinja::IsUIEnabled())
+		if (!context->IsInteractive())
 		{
-			// When headless, filter to the preferred architecture if one is configured.
 			vector<string> archPref = context->GetSettings()->Get<vector<string>>("files.universal.architecturePreference");
 			if (auto result = find_first_of(archPref.begin(), archPref.end(), architectures.begin(), architectures.end()); result != archPref.end())
 			{
+				// Filter to preferred architecture to support container auto-open policy
 				size_t archIndex = find(architectures.begin(), architectures.end(), *result) - architectures.begin();
 				context->SetAvailableFiles({architectures[archIndex]});
 				return false;
 			}
 
-			// Load the first architecture if no preference is found.
-			if (archPref.empty() && architectures.size())
+			// Preserve original headless load behavior when no architecturePreference is specified
+			if (!BinaryNinja::IsUIEnabled() && archPref.empty() && architectures.size())
 			{
 				context->SetAvailableFiles({architectures[0]});
 				return false;