QDS-13236 Update to Qt 6.8

This MR brings the following changes;

• chore: update to Qt6.8.0, EMSDK 3.1.56, and QtQuickDesigner Components to qds-dev-4.6-3-g20397e2
• cicd: support building for multithreaded and singlethread wasm binary
• enh: new window resizing method in C++

assigned to @hancerli

requested review from @thhartma

added 1 commit

• f36d67fc - chore: cleanup includes

Compare with previous version

merged