Setup Discourse instance for testing

@hiro got the discourse people to make us a test instance at https://forum.torproject.org.

In order to support the soft launch, TPA should get the following done:

• Obtain Administrator role access (either from @hiro or team@discourse.org)
• Identify and get in touch with the hosting provider

External hosting :

• Get information about hosting terms and any eventual applicable fees, if any
• Identify limitations (if any) of the hosted instance
• Check if plugins are available and test installation (eg. https://meta.discourse.org/t/header-search-theme-component/67959)
• Attempt have the instance moved to forum.torproject.net to comply with TPA-RFC-6 (caveat: could prompt some people to ask questions)
• Ask hosting provider if it's possible to setup .onion service for instance
• Evaluate usability of forum within the Tor network

Instance configuration:

• Test/enable mandatory 2FA for instance admins
• Test mailing-list mode (can the instance process incoming mail?)
• Test mailing-list mirroring (eg. https://qubes-os.discourse.group/c/mailing-lists-read-only-mirrors/20)
• Set up and evaluate Embedding Discourse Comments via Javascript on a test site
• Evaluate usability of forum when Javascript is disabled
• Identify and document anonymizing capabilities (how to enable)
• Identify and document telemetry capabilities (how to disable)

See also the Launch checklist.