Update issue templates

Author: bangetto

.github/ISSUE_TEMPLATE/missing-item.md

@@ -0,0 +1,17 @@
+---
+name: Missing Item
+about: An item is missing from the backport.
+title: "[Missing] "
+labels: missing item
+assignees: bangetto
+
+---
+
+**Server version:**
+**Client version:**
+
+**ViaVersion version:**
+**ViaBackwards version:**
+
+
+**Missing item:**

.github/ISSUE_TEMPLATE/swapped-items.md

@@ -0,0 +1,19 @@
+---
+name: Swapped Items
+about: Items have the wrong texture.
+title: "[Swapped] "
+labels: swapped items
+assignees: bangetto
+
+---
+
+**Server version:**
+**Client version:**
+
+**ViaVersion version:**
+**ViaBackwards version:**
+
+
+**Swapped Items list:**
+- Item A to Item B
+- Item B to Item A