Cardano Updates

- Rewrite the singleton-list `++` in hardforkViaConfig as `:` to satisfy
  hlint's "Use :" hint.
- Add scriv fragment documenting the previous commit's disabling of
  ExperimentalHardForksEnabled.

After ProtVer 12 became the experimental-gated version, Conway-era
testnets forged blocks with PV 12 in the header, which the Conway
BBody rule rejects (max PV = 11). Dropping the unconditional flag
from hardforkViaConfig makes the node fall back to ProtVer 11, which
Conway accepts, so the testnet chain progresses.

cardano-testnet: Default to `--update-time` and add `--no-update-time` flag

Otherwise we can't compile due to

error: builder for '/nix/store/jvg1kv1bjbl1m88qm02hdyq460pxg8gc-cardano-ledger-binary-lib-testlib-1.6.0.0.drv' failed with exit code 1;
       last 10 log lines:
       >         ‘withGenTerm cddlData (Cuddle.Name ruleName)’
       >       In the expression:
       >         withGenTerm cddlData (Cuddle.Name ruleName)
       >           $ roundTripAnnExample lbl version version trip
       >     |
       > 130 |           withGenTerm cddlData (Cuddle.Name ruleName) $
       >     |                                 ^^^^^^^^^^^^^^^^^^^^

- The experimental hard fork becomes `ProtVer 12`
- `ProtVer 11` is not the default

- Bump cardano-node version to 11.0
- Unconditionally enable ProtVer 11
- Unconditionally parse Dijkstra Genesis