Add table generator to markdown editor in UI

Description

Expand the UI markdown editor to automatically create and format tables.

Proposal

It could behave like a button that lets you select the column and rows and generates them on the textfield for easier editing.

Links / references

https://gitlab.zendesk.com/agent/tickets/76724

http://www.tablesgenerator.com/markdown_tables

https://atom.io/packages/markdown-table-editor