HackStudio: Add context option to set execution point while debugging

You can now right click in HackStudio's editor while debugging and
have the option to instantly move the current execution position to
the current line.

Userland/DevTools/HackStudio/Debugger/Debugger.h

@@ -34,6 +34,7 @@ public:
     static bool is_initialized();
 
     void on_breakpoint_change(const String& file, size_t line, BreakpointChange change_type);
+    bool set_execution_position(const String& file, size_t line);
 
     void set_executable_path(const String& path) { m_executable_path = path; }
     void set_source_root(const String& source_root) { m_source_root = source_root; }