Userland: static vs non-static constexpr variables

Problem:
- `static` variables consume memory and sometimes are less
  optimizable.
- `static const` variables can be `constexpr`, usually.
- `static` function-local variables require an initialization check
  every time the function is run.

Solution:
- If a global `static` variable is only used in a single function then
  move it into the function and make it non-`static` and `constexpr`.
- Make all global `static` variables `constexpr` instead of `const`.
- Change function-local `static const[expr]` variables to be just
  `constexpr`.

Userland/Services/WindowServer/Compositor.cpp

@@ -634,7 +634,7 @@ void Compositor::flip_buffers()
 
 void Compositor::run_animations(Gfx::DisjointRectSet& flush_rects)
 {
-    static const int minimize_animation_steps = 10;
+    constexpr int minimize_animation_steps = 10;
     auto& painter = *m_back_painter;
     Gfx::PainterStateSaver saver(painter);
     painter.set_draw_op(Gfx::Painter::DrawOp::Invert);