Update CL, Bots, and Free.law features and pages to the membership model

[mlissner]

There are a handful of things in CL that need updating to move us to the membership model...

Features:

• [x] /pay/ — This goes away. People get invoices from Xero instead.
• [x] /donate/ — This goes away. We can decide if we want to keep the old data or just delete it. (We should probably keep it.)
• [x] /help/donations/ — This goes to free.law as needed or to Neon if that makes more sense. The donate form in https://github.com/freelawproject/free.law/issues/132 should link to this if possible.
• [x] /donate/check/ — This goes away. Neon takes its place.
• [x] /badges/sign-up/ — This goes away, or we can create a custom form for it. TBD. I'll have to tell Justia.

Pages:

• [x] free.law/donate/ becomes a funnel for bots.law links and for free.law links, then takes people to the donation form on Neon.
• [ ] free.law/join/ is a new page, much like free.law/donate, but is the funnel for people coming from CourtListener.

Profile pages:

• [x] Old donation records don't show up, but a link to the new Neon membership portal does.
• [x] Recurring donations do show up if still active, with some kind of warning.
• [x] But main idea is that everybody uses the membership portal and donate.free.law.

[mlissner]

Recurring donations do show up if still active, with some kind of warning.

This was wrong. We're moving all recurring donations to Neon, so they don't need to be in the profile anymore.

We can decide if we want to keep the old data or just delete it. (We should probably keep it.)

Correct, we should keep it for some number of years. Why not.

[mlissner]

This is done.