Move all text stuff to its own folder

src/gpu/text/GrTextUtils.h

 /*
  * Copyright 2015 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef GrTextUtils_DEFINED
 #define GrTextUtils_DEFINED
 
@@ skipping 50 matching lines @@
                                   const char text[], size_t byteLength,
                                   const SkScalar pos[], int scalarsPerPosition,
                                   const SkPoint& offset, const SkIRect& clipBounds);
 private:
     static void BmpAppendGlyph(GrAtlasTextBlob*, int runIndex, GrBatchFontCache*,
                                GrBatchTextStrike**, const SkGlyph&, int left, int top,
                                GrColor color, GrFontScaler*);
 };
 
 #endif