@actions/artifact: convert to an ESM module

packages/artifact/jest.config.cjs

@@ -0,0 +1,29 @@
+module.exports = {
+  clearMocks: true,
+  moduleFileExtensions: ['js', 'ts'],
+  testEnvironment: 'node',
+  testMatch: ['**/__tests__/*.test.ts'],
+  moduleNameMapper: {
+    '^(\\.{1,2}/.*)\\.js$': '$1',
+    '^@actions/http-client$': '<rootDir>/../http-client/lib/index.js',
+    '^@actions/http-client/lib/auth$': '<rootDir>/../http-client/lib/auth.js',
+    '^@actions/github$': '<rootDir>/../github/lib/github.js',
+    '^@actions/github/lib/utils$': '<rootDir>/../github/lib/utils.js'
+  },
+  transform: {
+    '^.+\\.(ts|js)$': ['ts-jest', {
+      isolatedModules: true,
+      diagnostics: {warnOnly: true},
+      tsconfig: {
+        allowJs: true,
+        esModuleInterop: true,
+        module: 'commonjs',
+        moduleResolution: 'node'
+      }
+    }]
+  },
+  transformIgnorePatterns: [
+    '/node_modules/(?!(@octokit|@actions/github|@actions/http-client|universal-user-agent|before-after-hook)/)'
+  ],
+  verbose: true
+}