fix: Crashes when getting tabs into text editor (#2008)

This time it may be for good. 


### Implementation description
As requested I added the preprocessing functionality into the pattern
editor. I had to duplicate a few functions and update the c++ library to
version 20. but now I can make sure the pattern editor doesn't see a tab
again. I also removed the preprocessor from where it was before because
it is not needed anymore. The changes were tested using a file that used
tabs for all its white space. The file was pasted into the pattern
editor and imported as well. I both cases no crashes occurred and the
files had no tabs on them.

plugins/builtin/include/content/views/view_pattern_editor.hpp

@@ -73,7 +73,6 @@ namespace hex::plugin::builtin {
             return ImGuiWindowFlags_NoScrollbar | ImGuiWindowFlags_NoScrollWithMouse;
         }
 
-        std::string preprocessText(const std::string &code);
         void setPopupWindowHeight(u32 height) { m_popupWindowHeight = height; }
         u32 getPopupWindowHeight() const { return m_popupWindowHeight; }