BookmarkStyleFeaturesAvailable function

BookmarkStyleFeaturesAvailable loads the selected PDFium module when necessary and returns True when the optional FPDFBookmark_GetStyle entry point is exported

When the export is present every TBookmark produced by Bookmarks, Bookmark, BookmarkChildren and BookmarkFrom carries the outline item's /F text flags (ISO 32000-1 Table 153) in its Style set: posItalic for bit 1 and posBold for bit 2

Without the export the Style set stays empty for every bookmark; nothing else about bookmark reading changes

• The export is optional so deployments with an older pdfium.dll still load and enumerate outlines normally, only the style flags are missing
• TPdfOutlineStyle is the same set type the Pascal-side TPdfOutlineEditor in FPdfCompress writes, so styles written by the editor read back through the native API