`is.historical()` edge-cases

[RasmusSkytte]

Describe the bug
is.historical() is wrong. Documentation says a table is historical if it has checksum, from_ts, and until_ts; implementation returns true if it has any of them.

To Reproduce
N/A

Expected behaviour
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Screenshots
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Provide output from sessionInfo()
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• I have checked that the bug is not already described in open issues

Additional context
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