Add 'Balanced' rank option

[andrewmoise]

In the discussion about a better "Scaled" sort in bug #5210, it was recommended that I make a new sort option to implement the different sorting I described.

Looking at the change, I don't think applying this PR is the right way. I think the complexity and UX issues are such that it would be better to just amend the "Scaled" sort option in-place instead of adding a new sort option. But, I'm submitting this for discussion and to move the process forward. Comments are welcome. Having the option visible for purposes of comparison may be useful, for purposes of evaluating the change.

To actually work, this PR needs to go in alongside some other changes in other repos:

• Add a translation for "Balanced" in crates/utils/translations/translations/*.json
• Add an option for the "Balanced" sort in src/shared/components/common/sort-select.tsx in lemmy-ui, around line 141

Comments welcome.