Add support for new sort types as defaults

[micahmo]

Pull Request Description

The PR adds "Scaled" and "Controversial" to the possible default feed sorting options, and "Controversial" to the possible comment sorting options. If connected to an instance that doesn't support these types, Thunder's built-in defaults will be applied (Hot and Top, respectively). Along with these changes I added several new helpers to the LemmyClient class, such as a getter for the current version, and the ability to compare an arbitrary version against a feature. This turned out to be a bigger effort than I was expecting, so I think now (early in the release cycle) is a great time to get it in and tested!

Issue Being Fixed

Issue Number: #1002

Screenshots / Recordings

new-sort-demo.mp4

Checklist

• Did you update CHANGELOG.md?
• Did you use localized strings where applicable?
• Did you add semanticLabels where applicable for accessibility?

[hjiangsu]

LGTM! This should hopefully make version-restricted features easier to implement!