DevContainer: Recommend clang-18, and bump feature version

Author: https://github.com/ADKaster
Commit: https://github.com/SerenityOS/serenity/commit/751ddae7a2
Pull-request: https://github.com/SerenityOS/serenity/pull/23077
Reviewed-by: https://github.com/BertalanD
Reviewed-by: https://github.com/trflynn89 ✅

.devcontainer/devcontainer.json

@@ -7,7 +7,7 @@
         "ghcr.io/devcontainers/features/github-cli:1": {},
         "ghcr.io/devcontainers-contrib/features/pre-commit:1": {},
         "./features/serenity": {
-            "llvm_version": 16,
+            "llvm_version": 18,
             "enable_ladybird": true,
             "enable_serenity": true
         },

.devcontainer/features/serenity/devcontainer-feature.json

@@ -1,7 +1,7 @@
 {
     "name": "Serenity Development",
     "id": "serenity",
-    "version": "1.0.0",
+    "version": "1.0.1",
     "description": "Enable development of Serenity and Lagom libraries and applications",
     "options": {
         "llvm_version": {
@@ -9,6 +9,8 @@
             "proposals": [
                 15,
                 16,
+                17,
+                18,
                 "trunk"
             ],
             "default": 16,

.devcontainer/features/serenity/install.sh

@@ -3,7 +3,7 @@ set -e
 
 # Feature options
 
-LLVM_VERSION=${LLVM_VERSION:-16}
+LLVM_VERSION=${LLVM_VERSION:-18}
 ENABLE_LADYBIRD=${ENABLE_LADYBIRD:-true}
 ENABLE_SERENITY=${ENABLE_SERENITY:-true}