Improve admin by adding data tables

[katjam]

Is your feature request related to a problem? Please describe.
Consider: https://aarvy.me/blog/2019/09/21/datatables-with-bootstrap-4-minimal-setup-in-rails-6/

Describe the solution you'd like

• Add search (on name) to neighbourhood admin screens and pagination

Steps

• Update yarn depends
• Add relevant js library (probably a more up to date one than in that post)
• Update /app/components/admin_index/_admin_index.html.erb
• Possibly need to ensure that controllers have a javascript option in respond_to or it won't work
• strip out unwanted changes re. users
• Make datatables javascript work for Neightbourhood admins
• Make sure tests still pass

Further work to be done

• In app/datatables/neightbourhood_datatable.rb return sql for Neightbourhoods scoped by permission - right now only Neighbourhoods.all works
• Make search work on ancestry columns (currently can only search by name because it's data column has same name) #860
• Add edit link back into neighbourhood admin table table (was in actions column) #861
• Add sort to datatable columns in neighbourhood admin #862

[lexiwitch]

This fixes #793 also, doesn't it?

[kimadactyl]

This fixes #793 also, doesn't it?

it doens't fix it no - #793 would be an improvement, but this is perfectly adequate for now :)