Move `Time t` from `TEntry` to `TStorageItem`

[kjekac]

This may be cleaner because it allows us to infer names purely based on a storage item. On the other hand, it makes location extraction for name generation more difficult, because the pre- and the post-versions of each location will become separate location values which need to be matched to generate the correct assertions.

[Stereco-btc]

Hey @kjekac can i work on this issue

[kjekac]

Hey sorry, didn't see this. I haven't been maintaining Act for quite a few years now and so am not qualified to assess whether this is still desirable or not given the current codebase. Hopefully the active maintainers can support you in the PR you opened. Regardless the intention and enthusiasm is super appreciated!