Drop `T: Default` bound for array implementations

[roypat]

Moved from https://github.com/firecracker-microvm/firecracker/issues/1728, also touched on in https://github.com/firecracker-microvm/versionize/pull/47#issuecomment-1342930041

Currently, Versionize implementation for [T; N] require T: Default because we need to initialize the array somehow. We should track if at some point, Rust's MaybeUninit APIs mature enough to support dropping this bound.