add support of sections

src/jsMain/kotlin/dev/inmo/jsuikit/modifiers/UIKitSection.kt

@@ -0,0 +1,23 @@
+package dev.inmo.jsuikit.modifiers
+
+sealed class UIKitSection(vararg classes: String) : UIKitModifier {
+    override val classes: Array<String> = classes as Array<String>
+
+    sealed class Style(suffix: String) : UIKitSection("uk-section-$suffix") {
+        object Default : Style("default")
+        object Muted : Style("muted")
+        object Primary : Style("primary")
+        object Secondary : Style("secondary")
+    }
+
+    sealed class Size(suffix: String) : UIKitSection("uk-section-$suffix") {
+        object XSmall : Size("xsmall")
+        object Small : Size("small")
+        object Large : Size("large")
+        object XLarge : Size("xlarge")
+    }
+
+    object Overlap : UIKitSection("uk-section-overlap")
+
+    companion object : UIKitSection("uk-section")
+}