Add table caption as a type of thing (so we can style it properly and keep it with the table)
This issue is duplicated in the Ketida repo: https://gitlab.coko.foundation/ketida/ketida/-/issues/588
Context
Currently you can add a table, you could add a caption below it manually as a paragraph, but often it will separate across pages from the table which is not a good look at all. Tables need captions for reference purposes, especially in STEM subjects.
Proposal
When you add an image, when you click on the image you get a caption space below it but don't have to add a caption.
Design
Similar to image caption: table caption block appears below table automatically and can be deleted.
Alternatively add 'Add table caption' to table options allowing one caption to be added per table.