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* Enforce minimal varint encoding when decoding multiaddrs.
* Ensure codecs fit in 32bit integers for compatibility. We can increase the
size, but we'd need to change the `Protocol.Codec` type from `int` to `uint64`.

This is a defacto standard and is used by js-libp2p.

Ported from https://github.com/multiformats/go-multiaddr-dns/pull/17.
This was decided in https://github.com/multiformats/multiaddr/issues/22.