Remove wxStyledTextEvent::m_text and m_dragText.

These fields were unnecessary and duplicated m_cmdString inherited from the
base class.

Also use base class GetString() instead of the redundant GetText() and
GetDragText() in the code, even though these methods are still kept for
backwards compatibility.

See #16191.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@76486 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

interface/wx/stc/stc.h

@@ -6172,6 +6172,9 @@ public:
     int  GetKey()  const;
     int  GetModifiers() const;
     int  GetModificationType() const;
+    /**
+        @deprecated Use GetString() instead.
+     */
     wxString GetText() const;
     int  GetLength() const;
     int  GetLinesAdded() const;
@@ -6189,6 +6192,9 @@ public:
     int  GetAnnotationsLinesAdded() const;
     int  GetUpdated() const;
     
+    /**
+        @deprecated Use GetString() instead.
+     */
     wxString GetDragText();
     int GetDragFlags();
     wxDragResult GetDragResult();