feat: Add a field to DESCRIPTION to notify which version of rextendr the package was created with

[eitsupi]

Close #222

Like roxygen2 (r-lib/roxygen2#338), record the version of the rextendr used to create the package in DESCRIPTION to prevent the use of older versions.

It seems that the field name for this needs to start with Config/ ?
https://github.com/wch/r-source/blob/d1618921e670f1607da77ba850949f8312abdff6/src/library/tools/R/QC.R#L7204-L7213

[Ilia-Kosenkov]

Ok, I tested it locally, seems to work fine. However, I am not entirely sure about the path in the config name. Is this because we want to avoid R CMD check checking this field? Why Roxygen can have their own name while we cannot?

[yutannihilation]

Is this because we want to avoid R CMD check checking this field?

In my understanding, we don't really need this, but it's a common practice among tidyverse packages to use Config/ nowadays. In theory, we can put any field as the WRE says:

There is no restriction on the use of other fields not mentioned here (but using other capitalizations of these field names would cause confusion). Fields Note, Contact (for contacting the authors/developers9) and MailingList are in common use. Some repositories (including CRAN and R-forge) add their own fields.

It seems common field names like Roxygen are manually excluded: https://github.com/wch/r-source/blob/65710ee970c905903c497e806194b41b04385562/src/library/tools/R/utils.R#L1364-L1375. I guess the reason why roxygen2 has its own field is that it was born long before Config/ is popular.

[Ilia-Kosenkov]

Ok, sounds fair. @eitsupi, let me know if you are finished with this PR -- I need to force-merge it to bypass 32-bit failing CI.

[eitsupi]

Thank you all for your help.

@eitsupi, let me know if you are finished with this PR -- I need to force-merge it to bypass 32-bit failing CI.

The work is done and I would appreciate it if you could merge it if the field name is ok.
(The field name is obviously difficult to change later once release!)

[Ilia-Kosenkov]

Thank you for contributing @eitsupi !