feat(banner): 배너 레이아웃 계산 계약을 추가한다

app/src/main/java/kr/co/vividnext/sodalive/v2/widget/banner/BannerLayoutCalculator.kt

@@ -0,0 +1,23 @@
+package kr.co.vividnext.sodalive.v2.widget.banner
+
+object BannerLayoutCalculator {
+    private const val SIDE_INSET_DP = 20
+    private const val ITEM_SPACING_DP = 8
+
+    fun calculate(screenWidthDp: Int, density: Float): BannerLayoutSize {
+        val itemSizeDp = screenWidthDp - (SIDE_INSET_DP * 2)
+        return BannerLayoutSize(
+            itemWidthDp = itemSizeDp,
+            itemHeightDp = itemSizeDp,
+            sideInsetDp = SIDE_INSET_DP,
+            itemSpacingDp = ITEM_SPACING_DP
+        )
+    }
+}
+
+data class BannerLayoutSize(
+    val itemWidthDp: Int,
+    val itemHeightDp: Int,
+    val sideInsetDp: Int,
+    val itemSpacingDp: Int
+)