Add TextCtrl::DisableAllSmartSubstitutions for macOS

[trypsynth]

Summary

• Adds wxd_TextCtrl_DisableAllSmartSubstitutions (macOS only), wrapping wxTextCtrl::OSXDisableAllSmartSubstitutions, which is only declared on the OSX-specific wxTextCtrl header.
• Adds a disable_all_smart_substitutions method on the Rust TextCtrl widget, following the same manual-extern-declaration pattern used for the existing accessibility label helpers, since this symbol is guarded by #ifdef WXOSX and invisible to bindgen.

Motivation

Cocoa automatically substitutes straight quotes/hyphens for smart/curly variants in text fields unless a control opts out. For fields where a user's literal input should be preserved verbatim (search boxes, free text notes, and so on), this substitution is unwanted and currently cannot be disabled through wxDragon. wxWidgets already exposes OSXDisableAllSmartSubstitutions on the Cocoa port, it was just not wrapped yet.

Test plan

• cargo build -p wxdragon succeeds locally.