Revert "Revert "Fix potential memory leaks""

This reverts commit 2d33c20231 and
reapplies various patches for memory leaks.
The reason for the revert was a bug for a maximum duration interval
which caused sleep_for() to cause unpredictable behavior.

src/modules/upower/upower_tooltip.cpp

@@ -9,11 +9,10 @@
 namespace waybar::modules::upower {
 UPowerTooltip::UPowerTooltip(uint iconSize_, uint tooltipSpacing_, uint tooltipPadding_)
     : Gtk::Window(),
+      contentBox(std::make_unique<Gtk::Box>(Gtk::ORIENTATION_VERTICAL)),
       iconSize(iconSize_),
       tooltipSpacing(tooltipSpacing_),
       tooltipPadding(tooltipPadding_) {
-  contentBox = new Gtk::Box(Gtk::ORIENTATION_VERTICAL);
-
   // Sets the Tooltip Padding
   contentBox->set_margin_top(tooltipPadding);
   contentBox->set_margin_bottom(tooltipPadding);