Permit any string in address' entrypoint name

Clarification and motivation

We have

-- | Entrypoint name.
--
-- Empty if this entrypoint is default one.
-- Cannot be equal to "default", the reference implementation forbids that.
-- Also, set of allowed characters should be the same as in annotations.
newtype EpName = EpNameUnsafe { unEpName :: Text }
  deriving stock (Show, Eq, Ord, Generic)

The key thing here is "Also, set of allowed characters should be the same as in annotations". It turns out that sometimes EpName can contain other characters as well. See tezos/tezos#851

I would wait for some comments in that issue first. Maybe we can even keep morley more restrictive 🤷

Acceptance criteria

TODO, let's wait for comments in the upstream issue and then maybe decide something.