Combinators for TxBodyContent and related types

[newhoggy]

TxBodyContent has a function that constructs one of two default values for BuiltTx and ViewTx.

foo :: TxBodyContent BuildTx BabbageEra
foo = defaultTxBodyContent InBuildTx
  & setTxValidityRange someValidityRange
  & setTxIns someTxIns
  & setTxOuts someTxOuts
  & setTxOuts someMoreTxOuts

This is an alternative to #4458.

We don't seem to be able to agree on what the Semigroup instance should do out of a number alternatives and if there is confusion with choosing the behaviour, there will likely be confusion using the instance.

The idea behind this alternative is that we shouldn't arbitrarily choose a behaviour for the Semigroup instance because there is a high probability people who use our instances might assume it does something else.

This works with both ViewTx and BuildTx.

[ch1bo]

Left my 2 lovelaces as a user of this library.

[lehins]

I'd rather not introduce more classes/types

Just a minor note. No new types or classes are introduced in this PR, just new instances 😉

Use GADTs instead

[Jimbo4350]

Nice work 👍 . We definitely aren't interested in building ViewTx transactions, so you can remove support for that.

[ch1bo]

I like it and it's very much what we currently do in the upstream cardano-api. So hydra will be using this 👍

Comments addressed

[Jimbo4350]

LGTM! Just a couple naming suggestions.