Feat/frontend key access

[cyramic]

This does the following:

• Removes Frontend hosting on EC2
• Creates user to allow hosting on Heroku via key
• Some cleanup

Tested on:

• Staging LA site: https://staging.dataplatform.org.uk
• Staging Org site: https://staging-region.dataplatform.org.uk

[christina-moore]

I might need to chat this one through to fully understand what's going on here :)

[cyramic]

All this is doing is generating the access keys with the required permissions for Heroku so I can copy the result in to Heroku's env vars. :-)

Ideally I would have a setup that doesn't need this and users of the platform would just assume the role directly. That will be for later.