build(docker): refactor Dockerfile to enable caching of node_modules (#1550)

* ci: revert actions/cache version change and install GNU tar

* ci: do not potentially destroy Docker cache while building preview images

* build(docker): refactor Dockerfile to cache node_modules

* ci: remove Next.js caching

* build(docker): don't break arm builds

.github/workflows/snap.yaml

@@ -24,11 +24,6 @@ jobs:
     steps:
       - name: Checkout
         uses: actions/checkout@v2
-      - name: Cache Next.js build
-        uses: actions/cache@v2.1.0
-        with:
-          path: ${{ github.workspace }}/.next/cache
-          key: ${{ runner.os }}-nextjs-${{ hashFiles('**/package.json') }}
       - name: Install dependencies
         env:
           HUSKY_SKIP_INSTALL: 1