x11-toolkits/wlroots: move CONSOLEKIT as BASU to sysutils/seatd

• wlroots >= 0.14 is libseat-only per https://github.com/swaywm/wlroots/commit/7f0908546149
• WLR_SESSION currently defaults to libseat even if CONSOLEKIT is enabled
• mutter and plasma5-kwin if ever ported to libseat may want to use ConsoleKit2
• Enable BASU by default as the dependency is already pulled by sway and mako