rewrite includes to not need so much -Ifoo

Current strategy: everything from the top

Things to look at first are the manual changes:

   - added tools/rewrite_includes.py
   - removed -Idirectives from BUILD.gn
   - various compile.sh simplifications
   - tweak tools/embed_resources.py
   - update gn/find_headers.py to write paths from the top
   - update gn/gn_to_bp.py SkUserConfig.h layout
     so that #include "include/config/SkUserConfig.h" always
     gets the header we want.

No-Presubmit: true
Change-Id: I73a4b181654e0e38d229bc456c0d0854bae3363e
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/209706
Commit-Queue: Mike Klein <mtklein@google.com>
Reviewed-by: Hal Canary <halcanary@google.com>
Reviewed-by: Brian Osman <brianosman@google.com>
Reviewed-by: Florin Malita <fmalita@chromium.org>
diff --git a/docs/examples/IRect_intersect_2.cpp b/docs/examples/IRect_intersect_2.cpp
index 41506eb..800caa4 100644
--- a/docs/examples/IRect_intersect_2.cpp
+++ b/docs/examples/IRect_intersect_2.cpp
@@ -1,6 +1,6 @@
 // Copyright 2019 Google LLC.
 // Use of this source code is governed by a BSD-style license that can be found in the LICENSE file.
-#include "fiddle/examples.h"
+#include "tools/fiddle/examples.h"
 // HASH=b2db0573aacf99ca52776c5522459d02
 REG_FIDDLE(IRect_intersect_2, 256, 256, true, 0) {
 void draw(SkCanvas* canvas) {