fix: Update ctx BlockTime for simulations

[fkneeland-figure]

Description

When running simulation tests with wasmd I am running into this error: https://github.com/CosmWasm/wasmd/blob/14e58bfa81ea2ade0ff00ebd067ac0bc75e37cf8/x/wasm/types/types.go#L258

This is because when we are running in simulation mode we randomly create a date before the year 9999. However, if a date is after the year 2262 UnixNano will overflow and possibly return a negative number. To fix this I updated how we set the random genesis start time to be between the epoch and 200 years from now which means this error won't show itself again for another 40+ years.

Closes: #10466

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[fkneeland-figure]

This is ready for review

[ValarDragon]

Seems fine to me, as it only affects the CheckTx state

[alexanderbez]

using time.Now(), even if its just in CheckTx, scares me. Is there a reason we can't just default to having this change in NewEnv?

[fkneeland-figure]

@alexanderbez I would prefer to make the change here instead of in NewEnv as that code is run in production where as this setting of the time in context is only done in simulation mode (at least as far as I can tell). Is there something better I can use than time.Now() ?

[fkneeland-figure]

@alexanderbez I updated the way we create the genesis time to not be able to be so far into the future (it can still be up to 200 years from now) which also fixed this problem. Would you be okay with that solution?

Thanks for your feedback on this!

[fkneeland-figure]

@alexanderbez I had to make a minor change to fix tests that required timestamps to be in the future and consistent results based on the random seed. Could you take a look at those changes when you have a chance? This should be ready for merge.

[fkneeland-figure]

@alexanderbez @AmauryM can this branch be merged?