Cardano Updates

Final demo

As I added this, I noticed `OffsetKey` is included in `CursorTrace`, but this is
an internal type, so I changed it to `Maybe RawBytes` instead.

Final demo

Lift the restriction of minimum 8-byte keys for the compact index

This allows each `setup` to store its own snapshot based on the `--initial-size`
parameter. This makes it slightly easier to run multiple benchmarks with
different `--initial-size`s from the same session directory.

A small bug related to the merge schedule and union levels was unearted after
recent changes to key generators for the state machine tests.

```
❯ cabal run lsm-tree-test -- --quickcheck-replay="(SMGen 13447116701882578385 16048829213438376903,35)"   -p '$NF=="propLockstep_RealImpl_MockFS_IO"'
lsm-tree
  Test.Database.LSMTree.StateMachine
    propLockstep_RealImpl_MockFS_IO: FAIL (28.54s)
      *** Failed! Assertion failed (after 1 test and 196 shrinks):

      ...

1 out of 1 tests failed (28.54s)
```

The bug was that the last level was always removing `Delete` entries even if
there was union level. This is now fixed.

The most invasive change is that the `Realized` type family disappeared, but as
a result we also have to run the `IOSim` test with the `RealWorld` state token.
The `quickcheck-dynamic` library requires the return types of actions to be
`Typeable`, and if the state token appears in the return type of an action
(which it does in our tests), then the state token has to be typeable, which is
only really possible if we use `RealWorld`.

Rename the 'wp8' benchmarks to 'utxo' benchmarks

GHA: fix caching in `lint-generate-readme` job