Consider renaming `Lazy` to `LazyLock`

[tgross35]

Lazy was added in #89, back when the std implementation was called SyncLazy. It has since been renamed LazyLock, so it may be nice for consistency to change this crate's Lazy to the same.

Obviously this is very low priority, but changing the name at the next major version bump might make it more discoverable.

[zesterer]

I think spin broadly in sync with std::sync is a good idea, so I'm in favour of this.

[tgross35]

This has already been done in #185 right? It just would need a release.