Add optional volleyball set matches

[mrTyom]

What changed

• add an optional Play sets toggle for local games, disabled by default
• add a modern_volley rules entry with rally scoring and a two-point winning margin
• play best-of-five matches, using 25 points for modern sets and 15 for the deciding fifth set
• use 15-point sets for the existing standard and classic rules
• track set wins, alternate the first-serving player, and switch players between courts after each set
• keep configured input profiles attached to the left and right courts when players switch
• show set wins between each player's points and the match clock
• disable replay saving for multi-set matches, whose format is not supported by the replay file
• localize the new controls and set-transition messages

Impact

Existing local and network games retain their current behavior unless Play sets is enabled. Network play is unchanged. The existing classic rules remain the side-out scoring option; modern_volley supplies the modern rally-scoring format.

Validation

• Release x64 build with CMake and vcpkg
• existing and new Boost unit tests (blobbytest)
• header self-containment target (test-compile-headers)
• XML parsing for every language file and config.xml
• verified packaged rules.zip contains classic.lua and modern_volley.lua

The new tests cover 25:23, continued play at 25:24, 26:24, the 15-point fifth set, 3:0/3:1/3:2 match results, optional set mode, alternating service, and court changes.