community/althttpd: upgrade to 202203180956

For an inexperienced packager such as myself, this upgrade required a number of changes and I'm not sure I handled them correctly. The major change is the addition of native support for https. I discussed packaging with the upstream developers in this forum thread but there were some questions left unresolved. I've been holding off on the update until now and have just decided to make my best guesses which I think align with the upstream's intent.

The change to the pkgver, which I think might be problematic, is because upstream does not do versioned releases, although with the addition of https they now consider althttpd to be "2.0". Previously I was just using a date/time version because the fossil source code repository web UI allows tarballs to be generated based off a specific check in on the repo timeline. I'm still doing that with this MR, though I've added a "2.0" prefix to align with upstream's comments. Unfortunately, it looks like apk now considers this to be a downgrade:

(1/2) Downgrading althttpd (202201141852-r0 -> 2.0.202203180956-r0)
(2/2) Downgrading althttpd-openrc (202201141852-r0 -> 2.0.202203180956-r0)

I'm not sure what to do about that. My feeling is that I'm probably the only user of the package anyway so it's probably not a big deal, but...

The other change is the addition of the -doc subpackage. I'm not sure if sticking the contrib contents in the -doc package is the right thing to do though there does seem to be some precedent for it, see nsd-doc