internal: new shared_ptr and weak_ptr implementation (#5883)

moves std::shared_ptrs to a new implementation

Advantages:
- you can dereference a weak_ptr directly. This will obviously segfault on a nullptr deref if it's expired.
   - this is useful to avoid the .lock() hell where we are 100% sure the pointer _should_ be valid. (and if it isn't, it should throw.)
- weak_ptrs are still valid while the SP is being destroyed.
   - reasoning: while an object (e.g. CWindow) is being destroyed, its `weak_ptr self` should be accessible (the sp is still alive, and so is CWindow), but it's not because by stl it's already expired (to prevent resurrection)
   - this impl solves it differently. w_p is expired, but can still be dereferenced and used. Creating `s_p`s is not possible anymore, though.
   - this is useful in destructors and callbacks.

src/desktop/WLSurface.hpp

@@ -42,9 +42,9 @@ class CWLSurface {
     CSubsurface* getSubsurface();
 
     // desktop components misc utils
-    std::optional<CBox>                 getSurfaceBoxGlobal();
-    void                                appendConstraint(std::weak_ptr<CPointerConstraint> constraint);
-    std::shared_ptr<CPointerConstraint> constraint();
+    std::optional<CBox>    getSurfaceBoxGlobal();
+    void                   appendConstraint(WP<CPointerConstraint> constraint);
+    SP<CPointerConstraint> constraint();
 
     // allow stretching. Useful for plugins.
     bool m_bFillIgnoreSmall = false;
@@ -99,11 +99,11 @@ class CWLSurface {
     CSubsurface* m_pSubsurfaceOwner = nullptr;
 
     //
-    std::weak_ptr<CPointerConstraint> m_pConstraint;
+    WP<CPointerConstraint> m_pConstraint;
 
-    void                              destroy();
-    void                              init();
-    bool                              desktopComponent();
+    void                   destroy();
+    void                   init();
+    bool                   desktopComponent();
 
     DYNLISTENER(destroy);
     DYNLISTENER(commit);