Easier to set western piece set

[WandererXII]

Similar to this (https://github.com/WandererXII/lishogi/issues/826) but for non Japanese piece sets. New players who can't read kanji, might very quickly give up after seeing this:

I think setting western piece set by default if Japanese is not in the accepted languages header is not the right way. But maybe some toggle that is easy to find (next to the board, or in the top nav) for anon users might be useful.