Fix context menu command thread affinity

[YellowNest]

Summary

Invoke shell context-menu commands on the thread that created the IContextMenu object instead of passing the interface pointer to a separate STA thread.

Keep opencontaining non-blocking by using the existing SHOpenFolderAndSelectItemsSafe path, which performs the shell operation on the worker STA without moving the IContextMenu interface across apartments.

Why

The worker-STA invocation was introduced to avoid the Windows 11 "Open file location" delay. However, shell context-menu handlers can require invocation on the thread that created the context-menu object, as the existing special case for properties already demonstrates.

This also avoids passing a raw apartment-bound IContextMenu interface pointer to another STA.

Verification

• GitHub Actions Build completed successfully for commit dfbbb969ab28a125c3e1cdc89c86f50279b25ffa.
• Send to -> Desktop (create shortcut) creates the shortcut without freezing Open-Shell.
• Open file location still opens Explorer and selects the item.
• Properties still opens normally.

Fixes #2536

[ge0rdi]

Looks good to me.
Thank you.