Migrate player list gui to scenario

Move modules/gui/player-list into exp_scenario/gui/player_list using the
new exp_gui element API, matching the other scenario guis.

- Store the selected player and action on the container's player data
  instead of a datastore, folding the datastore on_update reactivity
  into explicit setter functions
- Switch the actions config to injected accessor functions and the
  exp-gui_player-list locale namespace
- Add the locale section, register in control.lua, and disable the
  legacy module in the file loader

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

exp_legacy/module/config/_file_loader.lua

@@ -24,7 +24,7 @@ return {
     --- GUI
     "modules.gui.rocket-info",
     "modules.gui.warp-list",
-    "modules.gui.player-list",
+    -- "modules.gui.player-list", -- migrated to exp_scenario/gui/player_list
     "modules.gui.vlayer",
     "modules.gui._role_updates",