Comfy::ArchiveHelper#comfy_archive_link_to_month should produce links to month padded with leading zero

[morgant]

Comfy::ArchiveHelper#comfy_archive_link_to_month only produces links with the month portion of the path padded with a leading zero if one specifically passes a month with a leading zero, for example: comfy_archive_link_to_month(2020, "07") will link to /blog/2020/07. Otherwise, it will not pad the month portion of the path, for example: comfy_archive_link_to_month(2020, 7) will link to /blog/2022/7.

While this is not technically incorrect, it'd be preferable to always pad the month portion of the path with a leading zero. To ensure that the URLs for monthly archives with the leading zero are considered canonical for SEO reasons, instead of those without the leading zero, we should probably also automatically redirect the non-padded month archives to the padded month archives.