## Issue Addressed
NA
## Proposed Changes
- Panic or return error if we overflow `usize` in SSZ decoding/encoding derive macros.
- I claim that the panics can only be triggered by a faulty type definition in lighthouse, they cannot be triggered externally on a validly defined struct.
- Use `Ordering` instead of some `if` statements, as demanded by clippy.
- Remove some old clippy `allow` that seem to no longer be required.
- Add comments to interesting clippy statements that we're going to continue to ignore.
- Create #1713
## Additional Info
NA
