Utils: Make aspect settings access implicit

Generally, aspects should use fromMap/toMap, but some older pages
use {from,to}Settings with always the same ICore::settings().

To make that less intrusive on the user code side, make that globally
implicit.

Task-number: QTCREATORBUG-29167
Change-Id: I29a8e23a31eb8061bb143e93931a07c6741eb7f9
Reviewed-by: Christian Stenger <christian.stenger@qt.io>

src/plugins/copilot/copilotoptionspage.cpp

@@ -8,8 +8,6 @@
 #include "copilotsettings.h"
 #include "copilottr.h"
 
-#include <coreplugin/icore.h>
-
 #include <utils/layoutbuilder.h>
 #include <utils/pathchooser.h>
 
@@ -95,7 +93,7 @@ public:
 
         setOnApply([] {
             CopilotSettings::instance().apply();
-            CopilotSettings::instance().writeSettings(Core::ICore::settings());
+            CopilotSettings::instance().writeSettings();
         });
     }
 };

src/plugins/copilot/copilotplugin.cpp

@@ -14,7 +14,6 @@
 
 #include <coreplugin/actionmanager/actionmanager.h>
 #include <coreplugin/editormanager/editormanager.h>
-#include <coreplugin/icore.h>
 #include <coreplugin/statusbarmanager.h>
 
 #include <languageclient/languageclientmanager.h>
@@ -58,7 +57,7 @@ void cycleSuggestion(TextEditor::TextEditorWidget *editor, Direction direction)
 
 void CopilotPlugin::initialize()
 {
-    CopilotSettings::instance().readSettings(ICore::settings());
+    CopilotSettings::instance().readSettings();
 
     restartClient();