Fix ruleset selector not updating to the first ruleset item until after `LoadComplete()`
Fix ruleset selector not updating to the first ruleset item until after `LoadComplete()`

This fixes the whole issue behind `Ruleset.Value` being null, by
updating `Current` on BDL rather than waiting for the base logic which
executes at `LoadComplete`.

This seems like something that should happen at the base `TabControl` class itself, by switching `Current` right after the first added tab item, rather than doing it on `LoadComplete`, but I'm not sure about changing framework logic outright, so fixing this locally until it occurs on other places.

peppy/osu,peppy/osu,ppy/osu,peppy/osu-new,smoogipoo/osu,NeoAdonis/osu,peppy/osu,ppy/osu,smoogipoo/osu,smoogipooo/osu,NeoAdonis/osu,ppy/osu,smoogipoo/osu,NeoAdonis/osu