fix(opengl): use Lazarus OpenGLContext

Replace OpenGLContextEx with OpenGLContext in MainForm, SpectrumViewOpengl, WaterfallViewOpengl, and WidebandView.

Switch the Lazarus project/program dependencies from LazOpenGLContextEx to LazOpenGLContext in ewsdr.lpi and ewsdr.lpr.

PixelScale was introduced in 092a202; restore the previous viewport/texture path: glViewport(0, 0, W, H), EnsureTexture(W, H), and UploadCurrentRow(W).

ewsdr.lpr

@@ -15,7 +15,7 @@ uses
   {$ENDIF}
   Interfaces,  // LCL platform
   WindowsDPI,
-  Forms, LazOpenGLContextEx,
+  Forms, LazOpenGLContext,
   MainForm, AudioOutput, DeviceForm, FlatButton, FreqDisplay, VfoOverlay,
   WDSP, WDSPEngine, WebPageHtml, WebServer, WebUtils, WinFirewall, WsClient,
   Settings, RadioController;