Tests/LibPDF: Add test for AES-encrypted PDF

I created this by typing "sup" into TextEdit.app on macOS 13.4,
hitting Cmd-P to bring up the print dialog, clicked the PDF button
at the bottom, changed Title and Author to "sup", clicked
"Security Options…", and checked "Require password to open document"
(with password "sup").

This file tests several things:
- It has a compressed stream as first object. This used to make the
  linearization dict detection logic assert.
- It uses AES as encryption key using version 4 of the encryption
  dict. This used to not be implemented.

Tests/LibPDF/CMakeLists.txt

@@ -10,6 +10,7 @@ set(TEST_FILES
     complex.pdf
     linearized.pdf
     non-linearized.pdf
+    password-is-sup.pdf
     type1.pdf
 )
 install(FILES ${TEST_FILES} DESTINATION home/anon/Documents/pdf)

Tests/LibPDF/TestPDF.cpp

@@ -48,3 +48,12 @@ TEST_CASE(truncated_pdf_header_issue_10717)
     auto document = PDF::Document::create(string.bytes());
     EXPECT(document.is_error());
 }
+
+TEST_CASE(encrypted_with_aes)
+{
+    auto file = MUST(Core::MappedFile::map("password-is-sup.pdf"sv));
+    auto document = MUST(PDF::Document::create(file->bytes()));
+    EXPECT(document->security_handler()->try_provide_user_password("sup"sv));
+    MUST(document->initialize());
+    EXPECT_EQ(document->get_page_count(), 1U);
+}