Use `ArrayVec` in `Encode` implementations

[DaniPopes]

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Describe the feature

Some types like StoredNibblesSubKey have a maximum fixed size, which can benefit from using ArrayVec<u8, N> to avoid using heap memory. However, BufMut must be implemented for it, which requires a wrapper struct like ArrayVecCompat<T, const N: usize> which implements BufMut like for vec.

Blocked on https://github.com/paradigmxyz/reth/issues/11351 since we may use our own trait

Additional context

No response