Remove a few call sites of SCH_SHEET::SetSize

This function is dangerous and should be used only by parsers, and not even
those, really.

For new objects, the size can be passed to the constructor.

eeschema/dialogs/panel_eeschema_color_settings.cpp

@@ -424,8 +424,10 @@ void PANEL_EESCHEMA_COLOR_SETTINGS::createPreviewItems()
         addItem( symbol );
     }
 
-    SCH_SHEET* s = new SCH_SHEET( nullptr, MILS_POINT( 4000, 1300 ) );
-    s->SetSize( wxSize( Mils2iu( 800 ), Mils2iu( 1300 ) ) );
+    SCH_SHEET* s = new SCH_SHEET(
+        /* aParent */ nullptr,
+        /* aPosition */ MILS_POINT( 4000, 1300 ),
+        /* aSize */ wxSize( Mils2iu( 800 ), Mils2iu( 1300 ) ) );
     s->GetFields().at( SHEETNAME ).SetText( wxT( "SHEET" ) );
     s->GetFields().at( SHEETFILENAME ).SetText( _( "/path/to/sheet" ) );
     s->AutoplaceFields( nullptr, false );

eeschema/sch_plugins/altium/sch_altium_plugin.cpp

@@ -1457,10 +1457,12 @@ void SCH_ALTIUM_PLUGIN::ParseSheetSymbol( int aIndex,
 {
     ASCH_SHEET_SYMBOL elem( aProperties );
 
-    SCH_SHEET*  sheet  = new SCH_SHEET( m_currentSheet, elem.location + m_sheetOffset );
+    SCH_SHEET*  sheet  = new SCH_SHEET(
+        /* aParent */ m_currentSheet,
+        /* aPosition */ elem.location + m_sheetOffset,
+        /* aSize */ elem.size );
     SCH_SCREEN* screen = new SCH_SCREEN( m_schematic );
 
-    sheet->SetSize( elem.size );
     sheet->SetBorderColor( GetColorFromInt( elem.color ) );
 
     if( elem.isSolid )

eeschema/sch_plugins/cadstar/cadstar_sch_archive_loader.cpp

@@ -2141,11 +2141,13 @@ void CADSTAR_SCH_ARCHIVE_LOADER::loadSheetAndChildSheets( LAYER_ID
     wxCHECK_MSG( m_sheetMap.find( aCadstarSheetID ) == m_sheetMap.end(), ,
                  "Sheet already loaded!" );
 
-    SCH_SHEET*     sheet = new SCH_SHEET( aParentSheet.Last(), aPosition );
+    SCH_SHEET*     sheet = new SCH_SHEET(
+        /* aParent */ aParentSheet.Last(),
+        /* aPosition */ aPosition,
+        /* aSize */ wxSize( aSheetSize ) );
     SCH_SCREEN*    screen = new SCH_SCREEN( m_schematic );
     SCH_SHEET_PATH instance( aParentSheet );
 
-    sheet->SetSize( (wxSize) aSheetSize );
     sheet->SetScreen( screen );
 
     wxString name = Sheets.SheetNames.at( aCadstarSheetID );