Add update-binfmts action

Meant to be used in conjunction with the Freedesktop SDK based images to
enable QEMU architecture emulation for flatpak-builder using
update-binfmts and its templates.

.github/workflows/flatpak-test.yml

@@ -116,3 +116,7 @@ jobs:
         working-directory: flat-manager
       - run: yarn run eslint .
         working-directory: flat-manager
+      - run: yarn install --also=dev
+        working-directory: update-binfmts
+      - run: yarn run eslint .
+        working-directory: update-binfmts

update-binfmts/.eslintrc.json

@@ -0,0 +1,14 @@
+{
+    "ignorePatterns": ["dist"],
+    "env": {
+        "commonjs": true,
+        "es2021": true,
+        "node": true
+    },
+    "extends": [
+        "standard"
+    ],
+    "parserOptions": {
+        "ecmaVersion": 12
+    }
+}

update-binfmts/action.yml

@@ -0,0 +1,8 @@
+name: "Update Binfmts"
+description: "Enable QEMU architecture emulation for flatpak-builder"
+branding:
+  icon: "package"
+  color: "blue"
+runs:
+  using: "node20"
+  main: "dist/index.js"