Move ExtendedTxEnvelope and impls to reth-primitives-traits

[mattsse]

Describe the feature

we have this in an example crate

reth/examples/custom-node/src/primitives/extended_op_tx_envelope.rs

Lines 27 to 35 in 1e33d4c

	/// A [`SignedTransaction`] implementation that combines two different transaction types.
	///
	/// This is intended to be used to extend existing presets, for example the ethereum or optstack
	/// transaction types.
	///
	/// Note: The other transaction type variants must not overlap with the builtin one, transaction
	/// types must be unique.
	#[derive(Debug, Clone, serde::Serialize, serde::Deserialize, Hash, Eq, PartialEq)]
	pub enum ExtendedTxEnvelope<BuiltIn, Other> {

we can promote this to the reth-primitives-trait crate entirely.

TODO

• move type to reth-primitives-traits/extended.rs
• adhere to all feature gates

Additional context

No response

[iTranscend]

can i take this?