Cardano Updates

Move EpochStateView, its background-thread setup, the STM-based wait
primitive, and the retry loops out of Testnet.Components.Query and into
a new module Testnet.Components.EpochStateView.

The new module carries a top-down haddock that explains how the writer
thread, the version counter, and awaitStateUpdateTimeout cooperate so
that future readers can learn the mechanism from one place rather than
piecing it together across Query.hs.

Testnet.Components.Query re-exports the public API so existing callers
do not need to change their imports.

Add plain DecCBOR instances for DijkstraBlockBodyRaw and
DijkstraBlockBody (needed for decoder equivalence tests), and a
custom ToExpr instance for DijkstraBlockBody. Add block_body to
the CddlSpec test suite.

Which introduced some flakiness in the e2e test.

Signed-off-by: dependabot[bot] <[email protected]>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>
Co-authored-by: Pat Losoponkul <[email protected]>

Replace mkUnsignedTx + mkByronWitness/mkShelleyWitness with
mkLedgerTx + mkByronWitnessLedger/mkShelleyWitnessLedger in
the duplicated test module.

All 8 golden hex string tests pass — ledger-native construction
produces byte-identical CBOR to the cardano-api construction.