refactor(primitvies): remove roundtrip-safe structs from primitives

[scarmuega]

No description provided.

[sterraf]

It seems necessary to implement the corresponding serde traits for KeepRaw, in order to have the same functionality. Should they be "transparent", i.e., ignoring the CBOR data? Or the derived ones for KeepRaw work well?

Today, derived traits are not the same for Minted vs plain structs:

#[derive(Serialize, Deserialize, Encode, Decode, Debug)]
pub struct Tx {
    ...

vs

#[derive(Encode, Decode, Debug, Clone)]
pub struct MintedTx<'b> {
    ...

[scarmuega]

@sterraf KeepRaw should be transparent for serde.