crashtesting: "unknown cell text: element" assert for text:bookmark #2

crashtesting: "unknown cell text: element" assert for text:bookmark #2

since...

commit 690a35680adad07c4ab79d82cd1531bb82fe4bc1
Date:   Sat Sep 10 16:32:46 2022 -0400

    tdf#103829 ods import: parse <text:tab/>

From documentation, it looks like we can also have
bookmark-start and bookmark-end, so adding these
even though no examples found.

I looked for how to insert bookmarks in calc - basically
no UI or menu (except one notebookbar, no calc documentation,
no abandoned bookmark code removal, no bookmark import code.

IIUC, in writer a bookmark is basically a field.
Perhaps it is similar in Calc? In any case, with this
limited wealth of information, I don't plan on trying
to fix the LO 4.1 loss of bookmark.

Change-Id: I44708a5c7d69ce37f688ec7beb243e08844dbfa8
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/140197
Tested-by: Justin Luth <jluth@mail.com>
Reviewed-by: Justin Luth <jluth@mail.com>