Perf: seperate skipped from non skipped in a seperate struct

[malik672]

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Describe the feature

this might look like an overkill for something so simple, but we can save memory by separating the skipped blobs from the unskipped ones, this works by removing the pad that would have been added based on the bool

also depending on the frequency of invalid transactions the Hashset as a data structure for it feels like it could be made simpler

Additional context

/// An iterator that returns transactions that can be executed on the current state (*best*
/// transactions).
///
/// The [`PendingPool`](crate::pool::pending::PendingPool) contains transactions that *could* all
/// be executed on the current state, but only yields transactions that are ready to be executed
/// now. While it contains all gapless transactions of a sender, it _always_ only returns the
/// transaction with the current on chain nonce.
pub(crate) struct BestTransactions<T: TransactionOrdering> {
    /// Contains a copy of _all_ transactions of the pending pool at the point in time this
    /// iterator was created.
    pub(crate) all: BTreeMap<TransactionId, PendingTransaction<T>>,
    /// Transactions that can be executed right away: these have the expected nonce.
    ///
    /// Once an `independent` transaction with the nonce `N` is returned, it unlocks `N+1`, which
    /// then can be moved from the `all` set to the `independent` set.
    pub(crate) independent: BTreeSet<PendingTransaction<T>>,
    /// There might be the case where a yielded transactions is invalid, this will track it.
    pub(crate) invalid: HashSet<TxHash>,
    /// Used to receive any new pending transactions that have been added to the pool after this
    /// iterator was static fileted
    ///
    /// These new pending transactions are inserted into this iterator's pool before yielding the
    /// next value
    pub(crate) new_transaction_receiver: Option<Receiver<PendingTransaction<T>>>,
    /// Flag to control whether to skip blob transactions (EIP4844).
    pub(crate) skip_blobs: bool,
}