Align everything to Node.js 16 (#22223)

* Update nvmrc to Node.js 16

* Update package.json minimum Node engine to 16

* Update README requirements to Node.js 16

* Update devcontainer Node.js version to 16

* Update devcontainer Dockerfile Node.js choices to LTS versions that are still in support/maintenance

* Pin CircleCI Node image to 16

* Fix YAML type issue

* Update CircleCI Node.js to 16.18 to match #22019

.devcontainer/Dockerfile

@@ -9,7 +9,7 @@ FROM mcr.microsoft.com/vscode/devcontainers/ruby:${VARIANT}
 # The value is a comma-separated list of allowed domains
 ENV RAILS_DEVELOPMENT_HOSTS=".githubpreview.dev"
 
-# [Choice] Node.js version: lts/*, 16, 14, 12, 10
+# [Choice] Node.js version: lts/*, 18, 16, 14
 ARG NODE_VERSION="lts/*"
 RUN su vscode -c "source /usr/local/share/nvm/nvm.sh && nvm install ${NODE_VERSION} 2>&1"
 

.devcontainer/docker-compose.yml

@@ -11,7 +11,7 @@ services:
         # Use -bullseye variants on local arm64/Apple Silicon.
         VARIANT: '3.0-bullseye'
         # Optional Node.js version to install
-        NODE_VERSION: '14'
+        NODE_VERSION: '16'
     volumes:
       - ..:/workspaces/mastodon:cached
     environment: