Improve tx type count observability in pool

[mattsse]

Describe the feature

currently we're only tracking txs by pool, which means that these metrics only track non pending blob txs:

reth/crates/transaction-pool/src/metrics.rs

Lines 34 to 37 in 098018d

	/// Number of transactions in the blob sub-pool
	pub(crate) blob_pool_transactions: Gauge,
	/// Total amount of memory used by the transactions in the blob sub-pool in bytes
	pub(crate) blob_pool_size_bytes: Gauge,

reth/crates/transaction-pool/src/pool/blob.rs

Line 12 in 098018d

/// A set of validated blob transactions in the pool that are __not pending__.

hence these metrics aren't useful to monitor how many blob transactions are currently in the entire txpool.

we would like this for all transaction types

TODO

• introduce new metrics for legacy,eip2930,1559,4844 count

we can either try tracking this on a per tx operation basis or by checking the total list by doing a fold over all transactions in the pool, which is more expensive.

reth/crates/transaction-pool/src/pool/txpool.rs

Lines 930 to 931 in 098018d

	/// _All_ transaction in the pool sorted by their sender and nonce pair.
	txs: BTreeMap<TransactionId, PoolInternalTransaction<T>>,

tracking all tx ops is more complex, so imo we're okay with updating these metrics when we update the pool for now this should be accurate enough:

reth/crates/transaction-pool/src/pool/txpool.rs

Line 432 in 098018d

self.metrics.performed_state_updates.increment(1);

Additional context

No response

[caglaryucekaya]

I'd like to work on this