DEV: Port discourse-table-builder theme component to core

[keegangeorge]

This PR is to port disourse-table-builder theme component to core.

Specifically:

• it adds SpreadsheetEditor component to core (converted to .gjs)
• updates post-decroations.js to include table edit functionality in addition to fullscreen table
• adds table builder related utilities (arrayToTable(), findTableRegex(), tokenRange()) to lib/utilities.js
• updates composer popup menu to add ability to insert tables
• adds acceptance/unit tests and system specs for table bulding/editing
• adds table builder related scss files
• adds new JS scripts jspreadsheet and jsuites for usage in SpreadsheetEditor component
• adds an updated bash script for updating table builder dependencies easily

[discoursebot]

This pull request has been mentioned on Discourse Meta. There might be relevant details there:

https://meta.discourse.org/t/table-builder/236016/118