M5: Import comments takes another PDF and copies its comments onto the same pages (#4595)

* M5: Import comments takes another PDF and copies its comments onto the same pages

Import comments read only XFDF, FDF, XML, XDP, CSV and text data files.
It now also takes a PDF: each comment of that PDF is copied onto the
page with the same number, at the same place, with its appearance
stream, its pop-up, its replies and its layer. Comments on pages past
the document's last page are left out, together with replies to them.
Links, form fields and redaction marks are not copied. A comment named
like one already on its page replaces it, as an XFDF or FDF import
does. A PDF without comments is refused with "nothing in the file
matches this document", and a PDF that needs a password is refused.

- organize: import_comments copies the comments with the page copier
  that Insert Pages uses, and registers the layers they use.
- engine: Edit::ImportData reads a file that starts with %PDF- as a PDF.
  Any other file goes to the data importer first, and is read as a PDF
  when that fails, %PDF- occurs in its first 1,024 bytes and the PDF
  reader opens it.
- ui: Comments > Import comments lists .pdf files; form.import_data
  lists the same files as before.
- automation: the doc_import_data description names the PDF case.
- parity: comment.import-from-pdf is shipped.

* Import comments: an annotation that is no comment keeps its name

A comment imported from a PDF replaced any annotation of the same /NM
on its page that was not locked, a redaction mark or a widget, so a
link, screen or 3D annotation of that name was overwritten. Only an
annotation whose subtype is one of the copied comment subtypes is
replaced now; for any other, the copy is added beside it without the
name. The subtype is read through an indirect reference.

* Import comments: index each page's annotations instead of scanning them per comment

* Import comments: a layer that BaseState OFF hides stays hidden

* Import comments: a PDF with binary bytes before its header imports on an XFA form, and two comments with one name both land

On an XFA form, a decode failure no longer stops the import when a PDF
header is in the first 1,024 bytes; the PDF's comments are copied. Two
incoming comments on one page with the same /NM no longer replace the
same comment: the first replaces it, and the second is added without
the name.

* Import comments: an inline annotation on the page is replaced by name

An annotation written inline in a page's /Annots is made an indirect
object before names are matched, so an incoming comment with its /NM
replaces it instead of being added beside it.

* Import comments: two new comments with one name keep it once

When no comment on the page has the name, the first incoming comment
keeps its /NM and each later one with the same name is added without it.

parity/acrobat-features.toml

@@ -4264,11 +4264,11 @@ title = "Import comments from another PDF"
 area = "E"
 tier = "P2"
 milestone = "M5"
-status = "planned"
-commands = []
-tools = []
-evidence = []
-notes = ""
+status = "shipped"
+commands = ["comment.import"]
+tools = ["doc_import_data"]
+evidence = ["crates/organize/src/comments.rs::comments_of_another_pdf_land_on_the_pages_with_the_same_numbers", "crates/organize/src/comments.rs::a_reply_on_an_earlier_page_reaches_its_comment_by_name", "crates/organize/src/comments.rs::a_comment_keeps_its_layer_and_the_layer_its_visibility", "crates/organize/src/comments.rs::a_long_thread_goes_with_its_first_comment_and_a_loop_of_replies_stays", "crates/organize/src/comments.rs::a_pdf_without_comments_copies_none", "crates/engine/src/tests.rs::importing_a_pdf_copies_its_comments", "crates/ui-egui/tests/it/pickers.rs::import_comments_takes_the_comments_of_another_pdf"]
+notes = "Import comments accepts a PDF beside XFDF and FDF. Each comment goes onto the page with the same number, at the same place, with its appearance, pop-up and replies; comments on pages past the document's last page are left out. A same-named comment is replaced, as with XFDF and FDF. Not yet: redaction marks are not copied, and a PDF that needs a password is refused."
 
 [[feature]]
 id = "comment.summarize"