Add value-returning match expressions

tools/vscode-gotlin/snippets/gotlin.code-snippets

@@ -80,6 +80,17 @@
     ],
     "description": "Exhaustive match over enum variants"
   },
+  "Exhaustive Match Expression": {
+    "prefix": "matchvalue",
+    "body": [
+      "val ${1:value} = match (${2:result}) {",
+      "    ${3:Result}::${4:Success}(${5:item}) -> ${5:item}",
+      "    ${3:Result}::${6:Failure}(${7:reason}) -> ${7:reason}",
+      "    $0",
+      "}"
+    ],
+    "description": "Return a typed value from an exhaustive enum match"
+  },
   "Recursive Structural Mapping": {
     "prefix": "mapto",
     "body": ["val ${1:target} = ${2:source}.mapTo<${3:Target}>()"],