Redo tx body construction, with era-dependent fields.

Introduce a TxBodyContent type containing all the tx body fields. This
type now covers all eras, including Byron. All the fields other than
inputs and outputs are era-dependent: whether they're supported, and if
so required or optional.

We introduce a slew of types to cover which fields are supported in
which eras. This makes a lot of things more uniform.

Also complete the conversion functions into the underlying ledger types.
This should now provide full support for the current Allegra and Mary
eras. It has stubs for the auxiliary scripts which will be supported in
the ledger shortly.

This patch does not update the tests or CLI. We may yet find we need
some more type classes, or extensions to existing classes to make using
this convenient.

cardano-api/src/Cardano/API.hs

@@ -114,24 +114,49 @@ module Cardano.API (
 
     -- * Building transactions
     -- | Constructing and inspecting transactions
+
+    -- ** Transaction bodies
     TxBody,
+    makeTransactionBody,
+    TxBodyContent(..),
+    makeByronTxBodyContent,
+    makeShelleyTxBodyContent,
+
+    -- ** Transaction Ids
     TxId,
     getTxId,
+
+    -- ** Transaction inputs
     TxIn(TxIn),
     TxIx(TxIx),
+
+    -- ** Transaction outputs
     TxOut(TxOut),
     TxOutValue(..),
-    AdaOnlyInEra(..),
-    MultiAssetInEra(..),
-    TTL,
-    TxFee,
-    MintValue(..),
-    makeByronTransaction,
-    makeShelleyTransaction,
-    SlotNo,
-    TxExtraContent,
-    txExtraContentEmpty,
-    Certificate,
+
+    -- ** Other transaction body types
+    TxFee(..),
+    TxValidityLowerBound(..),
+    TxValidityUpperBound(..),
+    SlotNo(..),
+    TxMetadataInEra(..),
+    TxAuxScripts(..),
+    TxWithdrawals(..),
+    TxCertificates(..),
+    TxUpdateProposal(..),
+    TxMintValue(..),
+
+    -- ** Era-dependent transaction body features
+    OnlyAdaSupportedInEra(..),
+    MultiAssetSupportedInEra(..),
+    ValidityUpperBoundSupportedInEra(..),
+    ValidityNoUpperBoundSupportedInEra(..),
+    ValidityLowerBoundSupportedInEra(..),
+    TxMetadataSupportedInEra(..),
+    AuxScriptsSupportedInEra(..),
+    WithdrawalsSupportedInEra(..),
+    CertificatesSupportedInEra(..),
+    UpdateProposalSupportedInEra(..),
 
     -- * Signing transactions
     -- | Creating transaction witnesses one by one, or all in one go.
@@ -176,15 +201,18 @@ module Cardano.API (
     TxMetadataJsonError (..),
     TxMetadataJsonSchemaError (..),
 
-    -- * Registering stake address and delegating
+    -- * Certificates
+    Certificate,
+
+    -- ** Registering stake address and delegating
     -- | Certificates that are embedded in transactions for registering and
     -- unregistering stake address, and for setting the stake pool delegation
     -- choice for a stake address.
     makeStakeAddressRegistrationCertificate,
     makeStakeAddressDeregistrationCertificate,
     makeStakeAddressDelegationCertificate,
 
-    -- * Registering stake pools
+    -- ** Registering stake pools
     -- | Certificates that are embedded in transactions for registering and
     -- retiring stake pools. This includes updating the stake pool parameters.
     makeStakePoolRegistrationCertificate,
@@ -193,7 +221,7 @@ module Cardano.API (
     StakePoolRelay,
     StakePoolMetadataReference,
 
-    -- ** Stake pool off-chain metadata
+    -- * Stake pool off-chain metadata
     StakePoolMetadata,
     validateAndHashStakePoolMetadata,
     StakePoolMetadataValidationError,