## Why this should be merged
The `types.Header` fields of both
[`coreth`](https://pkg.go.dev/github.com/ava-labs/coreth/core/types#Header)
and
[`subnet-evm`](https://pkg.go.dev/github.com/ava-labs/subnet-evm/core/types#Header)
have been modified such that their RLP encodings (i.e. block hashes)
aren't compatible with vanilla `geth` nor each other. This PR adds
support for arbitrary RLP encoding coupled with type-safe extra
payloads.
## How this works
Equivalent to #1 (`params`) and #44 (`types.StateAccount`) registration
of pseudo-generic payloads. The only major difference is the guarantee
of a non-nil payload pointer, which means that the payload hooks are
never called on nil pointers as this would make it difficult to decode
RLP into them.
## How this was tested
Round-trip RLP {en,de}coding via a registered stub hook.
---------
Signed-off-by: Arran Schlosberg <519948+ARR4N@users.noreply.github.com>
Co-authored-by: Quentin McGaw <quentin.mcgaw@gmail.com>
## Why this should be merged
There are 3 places at which we perform the same, sensitive logic to
access registered payloads and as we modify more types this is likely to
expand. (e.g. `types.Header`).
## How this works
Introduces `pseudo.Accessor` to abstract the reusable code.
## How this was tested
Existing unit tests. Note that the `types.StateAccount` tests needed a
minor refactor to provide the assertions with access to the
`ExtraPayloads[T]` without introducing generic types anywhere.
## Why this should be merged
Provides access to extra payloads registered on `types.SlimAccount`, not
just on regular `types.StateAccount`. This is a breaking syntax change
to have the method reflect the behaviour.
## How this works
Modify existing method to accept the `ExtraPayloadCarrier` interface
instead of `*StateAccount`. The interface is implemented by both
`*StateAccount` and `*SlimAccount`.
## How this was tested
Covered by existing testing.
* feat: `state.{Get,Set}Extra[SA any](*StateDB,types.ExtraPayloads,...)`
* test: `GetExtra()` at each point in `CreateAccount()` + `SetExtra()` lifecycle
* test: reverting extras to snapshot
* test: `GetExtra()` after `StateDB.Copy()` and writes to original
