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Description
In the process of untangling Resolution/FreqGroup/PeriodDtype/Offsets im finding it would be helpful if to_offset("year") behaved like to_offset("Y") etc. But apparently these are specifically deprecated.
This test was introduced here (commit but no PR) and is listed as closing #11854 and #12540, but neither of those really make it clear to me why we wouldn't allow these.
Any objection to having to_offset recognize these strings?