Remove (unused) SkImageEncoder.h includes (flutter/engine#40989)

I'm refactoring Skia's image codecs and noticed that although Flutter
includes this header, it doesn't seem to use any of the symbols from it:
`SkEncodeImage` and `SkEncodePixmap`.

This PR removes those includes and also adds some missing includes which
will aid future Skia cleanup CLs.

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there for submitting PRs.
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Objective-C, Java style guides].
- [ ] I listed at least one issue that this PR fixes in the description
above.
- [x] I added new tests to check the change I am making or feature I am
adding, or Hixie said the PR is test-exempt. See [testing the engine]
for instructions on writing and running engine tests.
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engine/src/flutter/flow/layer_snapshot_store.h

@@ -10,8 +10,10 @@
 #include "flutter/fml/logging.h"
 #include "flutter/fml/time/time_delta.h"
 
-#include "third_party/skia/include/core/SkImageEncoder.h"
+#include "third_party/skia/include/core/SkData.h"
 #include "third_party/skia/include/core/SkPictureRecorder.h"
+#include "third_party/skia/include/core/SkRect.h"
+#include "third_party/skia/include/core/SkRefCnt.h"
 #include "third_party/skia/include/core/SkSerialProcs.h"
 #include "third_party/skia/include/core/SkSurface.h"
 #include "third_party/skia/include/core/SkSurfaceCharacterization.h"

engine/src/flutter/flow/layers/offscreen_surface.cc

@@ -4,10 +4,11 @@
 
 #include "flutter/flow/layers/offscreen_surface.h"
 
-#include "third_party/skia/include/core/SkImageEncoder.h"
+#include "third_party/skia/include/core/SkColorSpace.h"
+#include "third_party/skia/include/core/SkImageInfo.h"
 #include "third_party/skia/include/core/SkPictureRecorder.h"
+#include "third_party/skia/include/core/SkPixmap.h"
 #include "third_party/skia/include/core/SkSerialProcs.h"
-#include "third_party/skia/include/core/SkSurface.h"
 #include "third_party/skia/include/core/SkSurfaceCharacterization.h"
 #include "third_party/skia/include/utils/SkBase64.h"
 

engine/src/flutter/flow/layers/offscreen_surface.h

@@ -10,6 +10,9 @@
 
 #include "flutter/display_list/dl_canvas.h"
 #include "flutter/display_list/skia/dl_sk_canvas.h"
+#include "third_party/skia/include/core/SkData.h"
+#include "third_party/skia/include/core/SkRefCnt.h"
+#include "third_party/skia/include/core/SkSize.h"
 #include "third_party/skia/include/core/SkSurface.h"
 
 class GrDirectContext;

engine/src/flutter/shell/common/rasterizer.cc

@@ -15,9 +15,11 @@
 #include "flutter/fml/time/time_point.h"
 #include "flutter/shell/common/serialization_callbacks.h"
 #include "fml/make_copyable.h"
-#include "third_party/skia/include/core/SkImageEncoder.h"
+#include "third_party/skia/include/core/SkImageInfo.h"
+#include "third_party/skia/include/core/SkMatrix.h"
 #include "third_party/skia/include/core/SkPictureRecorder.h"
 #include "third_party/skia/include/core/SkSerialProcs.h"
+#include "third_party/skia/include/core/SkSize.h"
 #include "third_party/skia/include/core/SkSurface.h"
 #include "third_party/skia/include/core/SkSurfaceCharacterization.h"
 #include "third_party/skia/include/utils/SkBase64.h"

engine/src/flutter/shell/common/rasterizer.h

@@ -27,7 +27,10 @@
 #include "flutter/shell/common/pipeline.h"
 #include "flutter/shell/common/snapshot_controller.h"
 #include "flutter/shell/common/snapshot_surface_producer.h"
+#include "third_party/skia/include/core/SkData.h"
 #include "third_party/skia/include/core/SkImage.h"
+#include "third_party/skia/include/core/SkRect.h"
+#include "third_party/skia/include/core/SkRefCnt.h"
 #include "third_party/skia/include/gpu/GrDirectContext.h"
 
 namespace flutter {