Break xfa_basic_data up to smaller files

xfa_basic_data is a large (>7k lines) file that is difficult to navigate. This
CL breaks the file up into smaller files more logical files.

Review-Url: https://codereview.chromium.org/2123343002
diff --git a/BUILD.gn b/BUILD.gn
index 91348ce..b0f8969 100644
--- a/BUILD.gn
+++ b/BUILD.gn
@@ -1363,6 +1363,12 @@
       "xfa/fxfa/parser/cxfa_widgetdata.cpp",
       "xfa/fxfa/parser/cxfa_widgetdata.h",
       "xfa/fxfa/parser/xfa_basic_data.cpp",
+      "xfa/fxfa/parser/xfa_basic_data_attributes.cpp",
+      "xfa/fxfa/parser/xfa_basic_data_element_attributes.cpp",
+      "xfa/fxfa/parser/xfa_basic_data_element_properties.cpp",
+      "xfa/fxfa/parser/xfa_basic_data_element_script.cpp",
+      "xfa/fxfa/parser/xfa_basic_data_enum.cpp",
+      "xfa/fxfa/parser/xfa_basic_data_packets.cpp",
       "xfa/fxfa/parser/xfa_basic_data.h",
       "xfa/fxfa/parser/xfa_basic_imp.cpp",
       "xfa/fxfa/parser/xfa_basic_imp.h",