layout: rethonk layouts from the ground up (#12890)

Rewrites layouts to be much smaller, and deal with much less annoying
BS. Improves the overall architecture, unifies handling of pseudotiling,
and various other improvements.

src/layout/algorithm/FloatingAlgorithm.cpp

@@ -0,0 +1,18 @@
+#include "FloatingAlgorithm.hpp"
+#include "Algorithm.hpp"
+#include "../space/Space.hpp"
+
+using namespace Layout;
+
+void IFloatingAlgorithm::recalculate() {
+    ;
+}
+
+void IFloatingAlgorithm::recenter(SP<ITarget> t) {
+    const auto LAST = t->lastFloatingSize();
+
+    if (LAST.x <= 5 || LAST.y <= 5)
+        return;
+
+    t->setPositionGlobal({m_parent->space()->workArea().middle() - LAST / 2.F, LAST});
+}