The eval plugin should use the same default language extensions as ghci.

While working on #1591 it was noticed that the current default language extensions for the eval plugin were different from those in ghci. It is advantageous that both are identical.

Related comment in context: https://github.com/haskell/haskell-language-server/pull/1596#issuecomment-804770960
