feat: ReuseListIterator for getAll() api

[twoeths]

Motivation

• avoid possible array allocation with getAll() api

#383 make it possible to provide an Array for getAll() api, however it could still spike due to array allocation

Description

• Implement ReusableListIterator which is a LinkedList, when it grows it only append some more items instead of allocating a big array
• Implement getAll*Iter() api to View and ViewDU to allow consumer to use ReusableListIterator
• On average, ReusableListIterator is only a bit faster than Array however the key thing is to reduce any spikes as much as possible due to gc

Testing

• This branch (lg1k) in the last 24h, 10m rate interval, there are ~3 spikes

• te/batch_hash_tree_root, md64, 10m rate interval, there are ~18 spikes

• This branch (lg1k) in the last 24h, 12h rate interval. It's only a little bit faster than te/batch_hash_tree_root

• te/batch_hash_tree_root, md64, 12h rate interval

[twoeths]

note that there are still spikes in lodestar, see ChainSafe/lodestar#6979