Splitting fpdfdoc/doc_* part I

BUILD.gn

Index: BUILD.gn
diff --git a/BUILD.gn b/BUILD.gn
index f7a6007e0c4029d6c8e7b1261bc3be86ced61aa4..f482a5b4c9040a4515cb13d88ffcdda6e50205ef 100644
--- a/BUILD.gn
+++ b/BUILD.gn
@@ -202,11 +202,21 @@ static_library("fpdfdoc") {
   sources = [
     "core/fpdfdoc/clines.cpp",
     "core/fpdfdoc/clines.h",
+    "core/fpdfdoc/cpdf_aaction.cpp",
+    "core/fpdfdoc/cpdf_action.cpp",
+    "core/fpdfdoc/cpdf_actionfields.cpp",
     "core/fpdfdoc/cpdf_annot.cpp",
     "core/fpdfdoc/cpdf_annotlist.cpp",
     "core/fpdfdoc/cpdf_apsettings.h",
+    "core/fpdfdoc/cpdf_bookmark.cpp",
+    "core/fpdfdoc/cpdf_bookmarktree.cpp",
+    "core/fpdfdoc/cpdf_docjsactions.cpp",
+    "core/fpdfdoc/cpdf_link.cpp",
+    "core/fpdfdoc/cpdf_linklist.cpp",
+    "core/fpdfdoc/cpdf_metadata.cpp",
     "core/fpdfdoc/cpdf_pagelabel.h",
     "core/fpdfdoc/cpdf_variabletext.cpp",
+    "core/fpdfdoc/cpdf_viewerpreferences.cpp",
     "core/fpdfdoc/cpvt_color.cpp",
     "core/fpdfdoc/cpvt_color.h",
     "core/fpdfdoc/cpvt_dash.h",
@@ -224,18 +234,13 @@ static_library("fpdfdoc") {
     "core/fpdfdoc/csection.h",
     "core/fpdfdoc/ctypeset.cpp",
     "core/fpdfdoc/ctypeset.h",
-    "core/fpdfdoc/doc_action.cpp",
     "core/fpdfdoc/doc_basic.cpp",
-    "core/fpdfdoc/doc_bookmark.cpp",
     "core/fpdfdoc/doc_form.cpp",
     "core/fpdfdoc/doc_formcontrol.cpp",
     "core/fpdfdoc/doc_formfield.cpp",
-    "core/fpdfdoc/doc_link.cpp",
-    "core/fpdfdoc/doc_metadata.cpp",
     "core/fpdfdoc/doc_ocg.cpp",
     "core/fpdfdoc/doc_utils.cpp",
     "core/fpdfdoc/doc_utils.h",
-    "core/fpdfdoc/doc_viewerPreferences.cpp",
     "core/fpdfdoc/doc_vt.cpp",
     "core/fpdfdoc/include/cpdf_aaction.h",
     "core/fpdfdoc/include/cpdf_action.h",