Add support in the stage strike app for rulesets with "pre-set free stage picks"

[Wolfy76700]

The stage ruleset for CrocoCup #5 in France has a very odd way of doing things, which happens as is:

The stage list (Which is a 9-stage full starter stage list) has access to two special stages, which are picked by each player at the begining of a set within a subset of the stages in game. This pick happens prior to proceeding with the stage bans.

Ideally we should support that use case in TSH, as well as the use case where the stage picks end up in the counterpick list. May be a rewrite thing though.