Migrate SkSurface::flush methods to skgpu::ganesh version

Follow-up part 1 to https://skia-review.googlesource.com/c/skia/+/698237

It was not obvious to me where the correct GrDirectContext would
be for these surfaces, so I used the helper to extract the context
from the surface (if one exists) and use that.

Change-Id: I477d82659767d581cc6a7b7df36bd471796b11e9
diff --git a/libs/hwui/pipeline/skia/SkiaOpenGLPipeline.cpp b/libs/hwui/pipeline/skia/SkiaOpenGLPipeline.cpp
index 17f30c2..0cac6b3 100644
--- a/libs/hwui/pipeline/skia/SkiaOpenGLPipeline.cpp
+++ b/libs/hwui/pipeline/skia/SkiaOpenGLPipeline.cpp
@@ -175,7 +175,7 @@
 
     {
         ATRACE_NAME("flush commands");
-        surface->flushAndSubmit();
+        skgpu::ganesh::FlushAndSubmit(surface);
     }
     layerUpdateQueue->clear();