Deprecate encore in favour of mdaencore

[IAlibay]

The encore code has been turned into a separate mdakit. We should deprecate it from core with the aim of removing in 3.0.

[orbeckst]

Are we going to remove the code and replace with mdaencore until 3.0 (as we did for hole2, psa, etc)?

[IAlibay]

Probably? I think we're still missing a set of wheels that are fully compatible with the current status of MDA though, might need to get that done first.

[orbeckst]

Deprecation should be added for 2.8.0, given that we keep sending people over to mdaencore when they open issues here.

[orbeckst]

(Even if we don't replace it with the kit.)

[IAlibay]

I think we're just missing the CF migration, I'll add it to my to-do list for later in the month.