Double check intended tree size in Rekor

[lkatalin]

The original Rekor uses tree sizes equivalent to Rust's i64. Rekor-rs mixes i32 and i64. Instead it should use only i64 unless there is a good reason to do otherwise.

I would suggest going through the src/rekor code to find all instances of a tree size (this is usually a field in other structs) and making sure they are all i64, perhaps adding a tree_size type somewhere that is an alias to i64 and making sure it is used throughout.

Refs from golang Rekor: https://github.com/sigstore/rekor/blob/547eb3cef9690bc97e73e35eb3bf1f40b18a3504/cmd/rekor-cli/app/log_info.go#L46 https://github.com/sigstore/rekor/blob/547eb3cef9690bc97e73e35eb3bf1f40b18a3504/pkg/sharding/ranges.go#L42

[jvanz]

@flavio I think we can close this issue. It seems fixed in PR #151.