Introduce 'Never' type as a safe alternative to always None options

Unfortunately, as documented in:

  https://github.com/IntersectMBO/cardano-ledger/issues/4571

  Some Option fields in the script context certificates are going to
  remain set to None, at least until the next Hard fork. There's a risk
  that people permanently lock their funds if they expect deposits on
  registration credentials to ever be `Some`.

  So, we introduce a special type that emulate an `Option` that can only
  ever be `None`. We call it `Never` and it is the first type of this
  kind (i.e. with constructors indexes not starting at 0).

examples/acceptance_tests/110/lib/foo.ak

@@ -0,0 +1,39 @@
+type Foo {
+  Foo(Int, Never)
+  Bar
+}
+
+test never_is_none() {
+  let none: Option<Void> = None
+
+  trace @"Never": Never
+  trace @"None": none
+
+  let data_never: Data = Never
+  let data_none: Data = none
+
+  data_never == data_none
+}
+
+test never_pattern_match() {
+  when Foo(14, Never) is {
+    Foo(x, Never) -> x == 14
+    Bar -> False
+  }
+}
+
+test never_assignment() {
+  let Never = Never
+  True
+}
+
+test never_wrong_cast() fail {
+  let data: Data = Some(42)
+  expect _: Never = data
+}
+
+test never_ok_cast() {
+  let none: Option<Void> = None
+  let data: Data = none
+  expect _: Never = data
+}