record upkeep year and use it for filtering checklist

[thomasp85]

Fix #1916

This PR adds two new functions: record_upkeep_year() which writes the year of the upkeep to Config/usethis/upkeep and last_upkeep_year() which retrieves this value or defaults to 2000 if it doesn't exist. These two functions are used in use_tidy_upkeep_issue() to automatically use the year of the last upkeep for filtering the produced checklist as well as incrementing the recorded year to the current year.

Further, this PR fixes what appears to be a bug/discrepancy in how year was used in make_upkeep_issue() depending on whether use_upkeep_issue() or use_tidy_upkeep_issue() was called

[jennybc]

My first / early reaction is that it feels like we have various year arguments lying around, some of which refer to the year of the upkeep and others which refer to the year of the previous upkeep. To be clear, this is not a situation of your creation -- it largely pre-existed.

Do you agree? Do you think this is a good occasion to make that situation less confusing?

Left a couple other comments.

[thomasp85]

Yeah, I was a bit perplexed about the duality of year when I started digging into this. But I also came to the conclusion that I'd rather not break anything so I kept it as is and instead changed the code to actually do as advertised.

I kinda don't think an argument for "current year" is needed at all - I can't imagine a situation where it would be anything other than what can be extracted from Sys.Date(). So if we were to change things up I'd move towards deprecating that argument and perhaps change the name of year were it refers to last upkeep year to something more descriptive

[thomasp85]

I have changed the code to record the full date rather than just the year. It still holds that we currently have nothing to use the added granularity for, but it is now recorded for the future.

As for the year argument, I'm afraid I don't have any strong feelings. The current situation is messy but I'm also hesitant to make a breaking change for the sake of cleaning it up

[thomasp85]

I'm happy to deprecate the year argument in use_upkeep_issue() as I think that is the (most) offending argument, but that is up to you

[thomasp85]

@jennybc I think this is ready now. If we merge it in we can ask people to call usethis:::record_upkeep_date(Sys.Date()) if they have already created the issue

[jennybc]

Thanks!