Upgrade to Rails 7.2

[jmthomas]

First we need to complete #1579 (upgrade to Ruby 3.3)

Rails 7.2 has made a nice improvement to ActionCable that we were previously working around: they now record a ping on every message: rails/rails@2a71de9. This is also noted in their release notes.

They also changed the name from recordPing to recordMessage so we'll have to remove all our instances of recordPing (since they're doing this now).

[jmthomas]

Some of this is OBE by the fact that we incorporated anycable in #1859