Implement 0-width pen consistently in wxGraphicsContext

Emulate a 1-pixel pen width as closely as possible.

This reverts:
334cf1cc91 (Take HiDPI scale into account for wxGCDC 0-width pen, 2021-04-03)
0d80050057 (Make wxGCDC behavior with 0-width wxPen consistent with MSW wxDC, 2021-03-02)

See #19077, #19115

src/common/graphcmn.cpp

@@ -572,6 +572,7 @@ wxGraphicsContext::wxGraphicsContext(wxGraphicsRenderer* renderer,
       m_enableOffset(false),
       m_window(window)
 {
+    m_contentScaleFactor = window ? window->GetContentScaleFactor() : 1.0;
 }
 
 wxGraphicsContext::~wxGraphicsContext()
@@ -605,6 +606,12 @@ void wxGraphicsContext::EnableOffset(bool enable)
     m_enableOffset = enable;
 }
 
+void wxGraphicsContext::SetContentScaleFactor(double contentScaleFactor)
+{
+    m_enableOffset = true;
+    m_contentScaleFactor = contentScaleFactor;
+}
+
 #if 0
 void wxGraphicsContext::SetAlpha( wxDouble WXUNUSED(alpha) )
 {