issue template for revdep checks

[tdhock]

we could make an issue template for posting revdep check failures that should be fixed before next CRAN release.
based on https://github.com/Rdatatable/data.table/wiki/Revdep-checks#steps-to-report-a-new-revdep-check-problem —
for data.table maintainers (not based on https://github.com/Rdatatable/data.table/wiki/revdep-issue-template which is for issues in other repos).

[mahjabinoyshi]

Hi, @tdhock, I am interested to work on this issue and add the revdep check failure template based on the two wiki pages.

[mahjabinoyshi]

Hi @tdhock ,
I’ve opened a PR that adds a revdep check failure issue template, based on the two wiki pages you linked: #7662. Please let me know if you’d like any changes.