## Why this should be merged
`goheader` linter apparently hasn't been running but now decided to and
is blocking another PR. It's not worth the time to investigatie why
(probably a version update).
## How this works
Update header comments as required.
## How this was tested
N/A
- Allow wallets and other clients to parse blocks from both coreth and subnet-evm without registering extra types
- Allow wallets and other clients to make their genesis/chain configurations without registering extra types
* chore: `golangci-lint` CI workflow
* fix: make `golangci-lint` happy
* chore: bump `actions/{checkout,setup-go}` versions
* chore: overhaul `.golanci.yml` config
* fix: all linter issues
* chore: exclude non-libevm linters + change deprecated option
* fix: add overflow check in example
* fix: try again; different local version?
* chore: this is trying my patience
* chore: enable `gci` and fix ordering
* chore: mark `ethclient/gethclient` test as flaky
* chore: mark `eth/catalyst` test as flaky
* refactor: extra types `C` + `R` are never plumbed as `*C` / `*R`
* refactor: force use of `pseudo.Constructor.Zero()` instead of `NilPointer()`
* feat: `pseudo.PointerTo()`
* feat: `params.ExtraPayloadGetter[C,R].PointerFromChainConfig(...) *C` and `Rules => *R` equiv
* test: shallow copy of `ChainConfig`/`Rules` includes extras
* feat: `params.ChainConfig` extra payload can use root JSON
* refactor: simplify `ChainConfig.UnmarshalJSON()` branches
* fix: change redundant `assert` to `require` for simplicity
