Move permission constants to constants/access_permissions.h.

Move them out of core/fpdfapi/parser/cpdf_document.h, remove "FPDF" from
their names, and make them real constants.

Change-Id: Ib93027dd1321be76b23a277fcc6a91a387099074
Reviewed-on: https://pdfium-review.googlesource.com/c/pdfium/+/65620
Commit-Queue: Lei Zhang <thestig@chromium.org>
Reviewed-by: Tom Sepez <tsepez@chromium.org>
diff --git a/constants/BUILD.gn b/constants/BUILD.gn
index 4c10fed..4489b66 100644
--- a/constants/BUILD.gn
+++ b/constants/BUILD.gn
@@ -6,6 +6,7 @@
 
 source_set("constants") {
   sources = [
+    "access_permissions.h",
     "annotation_common.h",
     "annotation_flags.h",
     "form_fields.h",