chore: add syntax parser directive to Dockerfile (#72380)

## What?
Add [`syntax`](https://docs.docker.com/reference/dockerfile/#syntax)
parser directive to the first line of the
[Dockerfile](https://docs.docker.com/reference/dockerfile/).

## Why?
To declare the Dockerfile syntax version to use for the build.
If unspecified, [BuildKit](https://docs.docker.com/build/buildkit/) uses
a bundled version of the Dockerfile frontend.

## How?
Append `# syntax=docker.io/docker/dockerfile:1` to the top of the
[Dockerfile](https://docs.docker.com/reference/dockerfile/).

Co-authored-by: JJ Kasper <[email protected]>

Author: JamBalaya56562

.devcontainer/Dockerfile

@@ -1,3 +1,5 @@
+# syntax=docker.io/docker/dockerfile:1
+
 # [Choice] Node.js version (use -bullseye variants on local arm64/Apple Silicon): 18, 16, 14, 18-bullseye, 16-bullseye, 14-bullseye, 18-buster, 16-buster, 14-buster
 ARG VARIANT=20-bullseye
 FROM mcr.microsoft.com/vscode/devcontainers/javascript-node:0-${VARIANT}

.devcontainer/base.Dockerfile

@@ -1,3 +1,5 @@
+# syntax=docker.io/docker/dockerfile:1
+
 # [Choice] Node.js version (use -bullseye variants on local arm64/Apple Silicon): 18-bullseye, 16-bullseye, 14-bullseye, 18-buster, 16-buster, 14-buster
 ARG VARIANT=20-bullseye
 FROM node:${VARIANT}

.github/actions/next-stats-action/Dockerfile

@@ -1,3 +1,5 @@
+# syntax=docker.io/docker/dockerfile:1
+
 FROM ubuntu:22.04
 
 LABEL com.github.actions.name="Next.js PR Stats"

examples/with-docker-compose/next-app/dev.Dockerfile

@@ -1,3 +1,5 @@
+# syntax=docker.io/docker/dockerfile:1
+
 FROM node:18-alpine
 
 WORKDIR /app

examples/with-docker-compose/next-app/prod-without-multistage.Dockerfile

@@ -1,3 +1,5 @@
+# syntax=docker.io/docker/dockerfile:1
+
 FROM node:18-alpine
 
 WORKDIR /app

examples/with-docker-compose/next-app/prod.Dockerfile

@@ -1,3 +1,5 @@
+# syntax=docker.io/docker/dockerfile:1
+
 FROM node:18-alpine AS base
 
 # Step 1. Rebuild the source code only when needed

examples/with-docker-multi-env/docker/development/Dockerfile

@@ -1,3 +1,5 @@
+# syntax=docker.io/docker/dockerfile:1
+
 FROM node:18-alpine AS base
 
 # 1. Install dependencies only when needed

examples/with-docker-multi-env/docker/production/Dockerfile

@@ -1,3 +1,5 @@
+# syntax=docker.io/docker/dockerfile:1
+
 FROM node:18-alpine AS base
 
 # 1. Install dependencies only when needed

examples/with-docker-multi-env/docker/staging/Dockerfile

@@ -1,3 +1,5 @@
+# syntax=docker.io/docker/dockerfile:1
+
 FROM node:18-alpine AS base
 
 # 1. Install dependencies only when needed

examples/with-docker/Dockerfile

@@ -1,3 +1,5 @@
+# syntax=docker.io/docker/dockerfile:1
+
 FROM node:18-alpine AS base
 
 # Install dependencies only when needed