Fix crash in Pattern Language syntax highlighting for self-inheriting structs (#2546)

``` rust
struct Rec : Rec {
};
```

Prevent infinite recursion in appendInheritances by erasing processed
inheritance entries during traversal, and safely iterate over
m_inheritances in appendInheritances to avoid
modification-during-iteration issues.

Co-authored-by: paxcut <53811119+paxcut@users.noreply.github.com>

plugins/builtin/include/content/text_highlighting/pattern_language.hpp

@@ -218,7 +218,7 @@ namespace hex::plugin::builtin {
         std::string getVariableTypeName();
         /// Append the variable definitions of the parent to the child
         void appendInheritances();
-        void recurseInheritances(std::string name);
+        void recurseInheritances(std::string name, size_t depth = 0);
         ///Loads a map of identifiers to their token id instances
         void loadInstances();
         /// Replace auto with the actual type for template arguments and function parameters