Eeschema, *.kicad_pro file: Use for the root sheet the canonical name "Root"

Previously, the translated name was stored in file.

Fixes https://gitlab.com/kicad/code/kicad/-/issues/19262

(cherry picked from commit d51c7372b4)

eeschema/files-io.cpp

@@ -1255,7 +1255,9 @@ bool SCH_EDIT_FRAME::SaveProject( bool aSaveAs )
 
             wxCHECK2( screen, continue );
 
-            sheets.emplace_back( std::make_pair( screen->GetUuid(), sheet->GetName() ) );
+            // For the root sheet we use the canonical name ( "Root" ) because its name
+            // cannot be modified by the user
+            sheets.emplace_back( std::make_pair( screen->GetUuid(), wxT( "Root" ) ) );
         }
         else
         {