default balance algo determine whether to pick loser_picks or split_noobs depending on circumstances

[jauggy]

Feature

This PR creates a new balance algo called "default" which becomes the default. It will call

If team size != 2 then call loser_picks
Otherwise if at least one newish player call split_noobs
Otherwise call loser_picks

Finally complaints over years where people say that new players are overrated can be put to rest. I have been observing multiple noob lobby games with split_noobs and am happy with the results (other than the chev icon being wrong for an unknown reason sometimes).

In SPADS we would later need to make a change to make loser_picks not voteable, but instead make default voteable instead.

Testing

You can go to website and pick default from the balance dropdown when inspecting a match

[jauggy]

Updated based on feedback.

@L-e-x-o-n as requested the default balance algorithm is now in admin config. Have set to "loser_picks" but can change to "default".