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/Applications/SpaceAnalyzer/TreeMapWidget.cpp

@@ -5,6 +5,7 @@
  */
 
 #include "TreeMapWidget.h"
+#include <AK/Array.h>
 #include <AK/NumberFormat.h>
 #include <LibGUI/Painter.h>
 #include <LibGUI/WindowServerConnection.h>
@@ -24,7 +25,7 @@ TreeMapWidget::~TreeMapWidget()
 {
 }
 
-static const Color colors[] = {
+static constexpr Array colors = {
     Color(253, 231, 37),
     Color(148, 216, 64),
     Color(60, 188, 117),