Random UI / QoL improvements

[gridhead]

Was going to do some PRs for these, but kept getting delayed and you've pinged me a couple of times ... so issues up for grabs:

1. Add some limits. Maybe Fedora proxies take care of most of this, but maybe not and probably shouldn't rely on them without a warning or something: https://adam-p.ca/blog/2022/01/golang-http-server-timeouts/ ... as it says click through to Filippo Valsorda’s post.
2. Binary to source repos, and back: A bunch of packages have different names in source or binary form, as long as you can map which repos. are the binary/source variants of others then it should be easy to redirect.
3. Add router.Get("/{vers}/", ...) which prints html listing changelog/pkg/files/srcpkg/
4. Add router.Get("/{vers}/pkg/", ...) which lists the packages (maybe json?). Dito. for the changelog/files/etc.
5. Add package size to the package data.
6. Add installed size to the package data.
7. You only do "release" repos. Simple fix is to add -updates and -updates-testing (not sure if anyone cares about -debuginfo) to all the ones that have those?
8. Adding the active CentOS stream repos.
9. This is a bigger one, and maybe deserves it's own issue: Have a way to diff between two things. Eg. router.Get("/{vers}/diff/{vers2}/pkg/", ...)

This ticket was originally opened by James Antill under the gridhead/metasource namespace.