[Bug Report]: Headers nested within other elements are not assigned IDs for Page Navigation #3058

Describe the Bug

In the top left of a page where you got the "Page navigation" section, there are links with anchors to get the user to the title on click. But in my case the title have no id so the anchors link are not working (Example : https://bookstackuri.com/books/bookname/page/pagename#

Steps to Reproduce

1. Create a page
2. Create a table
3. Create some headers (tiny headers => h5) in the table
4. Once created, visit the page
5. Head to the "page navigation" section (top left) and click on on or more headers

Expected Behaviour

The element (in my case h5) should have an id when being created so that the system can generate a correct anchor link

Screenshots or Additional Context

I'm observing this bug in 21.10.03, but I believe the page was created under version 0.30 (approximately)

Exact BookStack Version

21.10.03 or +/-0.30

PHP Version

7.4

Hosting Environment

Ubuntu 20.04

EDIT : I can work on it if needed
EDIT 2 : steps to reproduce update