* feat: pseudo-generic extra payloads in `params.ChainConfig` and `params.Rules`
* feat: `params.ExtraPayloadGetter` for end-user type safety
* refactor: payloads only available through `params.ExtraPayloadGetter`
* chore: make `libevm/examples/extraparams` a `params` testable example
* doc: `libevm/pseudo` package comments and improved readability
* doc: `params.*Extra*` comments and improved readability
* doc: `params.ExtraPayloadGetter` comments and improved readability
* doc: `params/config.libevm_test.go` comments and improved readability
* refactor: simplify `params.ChainConfig.UnmarshalJSON()`
* refactor: abstract new/nil-pointer creation into `pseudo.Constructor`s
* feat: precompile override via `params.Extras` hooks
* doc: flesh out `PrecompileOverride()` in example
* doc: complete commentary and improve readability
* refactor: `ChainConfig.Hooks()` + `Rules` equivalent
* chore: rename precompiles test file in keeping with geth equivalent
* feat: stateful precompiles + allowlist hooks
The allowlist hooks are included in this commit because they allow for the same functionality as stateful precompiles in `ava-labs/coreth` and `ava-labs/subnet-evm`.
* fix: `StateTransition.canExecuteTransaction()` used `msg.From` instead of `To`
* test: `params.RulesHooks.CanCreateContract` integration
* test: `params.RulesHooks.CanExecuteTransaction` integration
* test: `vm.NewStatefulPrecompile()` integration
* refactor: simplify test of `CanCreateContract`
* refactor: abstract generation of random `Address`/`Hash` values
* doc: full documentation + readability refactoring/renaming
* fix: remove circular dependency in tests
