UI: Add white icons for dock titles

- Add pop-out and close svg icons
- Update all dark themes qss with the new icons

UI/data/themes/Acri.qss

@@ -154,6 +154,11 @@ QListWidget QLineEdit {
 }
 
 /* Dock stuff */
+QDockWidget {
+	titlebar-close-icon: url('./Dark/Close.svg');
+	titlebar-normal-icon: url('./Dark/Popout.svg');
+}
+
 QDockWidget {
 	background: #181819;
 	border: none;
@@ -182,6 +187,7 @@ QDockWidget::float-button {
 	subcontrol-position: top right;
 	subcontrol-origin: padding;
 	right: 0px;
+	margin: 0px;
 }
 
 QDockWidget::float-button {

UI/data/themes/Dark.qss

@@ -119,6 +119,11 @@ SourceTree QLineEdit {
 
 /* Dock Widget */
 
+QDockWidget {
+	titlebar-close-icon: url('./Dark/Close.svg');
+	titlebar-normal-icon: url('./Dark/Popout.svg');
+}
+
 QDockWidget::title {
     text-align: center;
     background-color: rgb(70,69,70);

UI/data/themes/Dark/close.svg

+<svg class="feather feather-plus" fill="none" stroke="#FFF" stroke-linecap="round" stroke-linejoin="round" stroke-width="2" version="1.1" viewBox="0 0 30 30" xmlns="http://www.w3.org/2000/svg"><line x1="2" x2="28" y1="2" y2="28" /><line x1="2" x2="28" y1="28" y2="2" /></svg>

UI/data/themes/Dark/popout.svg

+<svg class="feather feather-plus" fill="none" stroke="#FFF" stroke-linecap="round" stroke-linejoin="round" stroke-width="2" version="1.1" viewBox="0 0 40 40" xmlns="http://www.w3.org/2000/svg"><rect x="2" y="2" width="24" height="20" /><rect x="2" y="2" width="24" height="4" style="fill:#fff" /><rect x="14" y="18" width="24" height="20" /><rect x="14" y="18" width="24" height="4" style="fill:#fff" /></svg>

UI/data/themes/Rachni.qss

@@ -188,6 +188,11 @@ QListWidget::item:hover:!active {
 /* --- Dock widget --- */
 /***********************/
 
+QDockWidget {
+	titlebar-close-icon: url('./Dark/Close.svg');
+	titlebar-normal-icon: url('./Dark/Popout.svg');
+}
+
 QDockWidget {
 	background: rgb(49, 54, 59); /* Blue-gray */
 	border: 1px solid rgb(58, 64, 69); /* Light Blue-gray */