chore(devcontainers): Move post create command to a script (#4090)

- it can be linted and has IDE code-completion
- we can add a lot more things to the script without sacrificing readability

.devcontainer/devcontainer.json

@@ -31,7 +31,7 @@
   ],
 
   // Use 'postCreateCommand' to run commands after the container is created.
-  "postCreateCommand": "yarn && yarn build:public && cp -n /workspaces/${localWorkspaceFolderBasename}/packages/server/.env-example /workspaces/${localWorkspaceFolderBasename}/packages/server/.env && cp -n /workspaces/${localWorkspaceFolderBasename}/packages/frontend-2/.env.example /workspaces/${localWorkspaceFolderBasename}/packages/frontend-2/.env",
+  "postCreateCommand": "/workspaces/${localWorkspaceFolderBasename}/.devcontainer/postCreateCommand.sh",
 
   // Configure tool-specific properties.
   // "customizations": {},

.devcontainer/postCreateCommand.sh

@@ -0,0 +1,17 @@
+#!/usr/bin/env bash
+set -eox pipefail
+
+echo "Running postCreateCommand.sh"
+
+# determine where the script is located, navigate into that directory, then find the root of the git repo in which it is located
+SCRIPT_DIR=$( cd -- "$( dirname -- "${BASH_SOURCE[0]}" )" &> /dev/null && pwd )
+cd "${SCRIPT_DIR}"
+GIT_ROOT="$(git rev-parse --show-toplevel)"
+
+echo "Setting up environment variables by copying .env files"
+cp -n "${GIT_ROOT}/packages/server/.env-example" "${GIT_ROOT}/packages/server/.env" || true
+cp -n "${GIT_ROOT}/packages/frontend-2/.env.example" "${GIT_ROOT}/packages/frontend-2/.env" || true
+
+echo "Installing nodejs dependencies and building shared packages"
+yarn
+yarn build:public