feat(utils): Implement get_size_hint for default impls

[PhilippGackstatter]

Implements get_size_hint for the types that are implemented by default.

Currently, crates that call u8.get_size_hint() get the default value of 0 which makes it harder to implement get_size_hint for custom types, since they cannot simply call get_size_hint on the contained types recursively. This PR fixes that.

This change is non-breaking.

See also 0xPolygonMiden/miden-base#895 (review) for more context.

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[irakliyk]

Thank you! I left one comment inline - but other than that, it looks great.

[irakliyk]

All looks good! Thank you!