Move some build steps to gulp (#12127)

* chore: move generate-standalone to gulp tasks

* move build-flow-typings to gulp tasks

* chore: move build-typescript-typings to gulp tasks

* move generate-type-helpers to gulp tasks

* chore: include build-typings and generate-type-helpers in gulp build

* update generate-standalone comments

* address review comments

* chore: revert build-typings refactor

* fix: run build-typings in build-no-bundle

packages/babel-standalone/scripts/generate.js

@@ -1,37 +0,0 @@
-// @flow
-const pluginConfig = require("./pluginConfig.json");
-const path = require("path");
-const chalk = require("chalk");
-const camelCase = require("lodash/camelCase");
-const format = require("../../../scripts/utils/formatCode");
-const writeFile = require("../../../scripts/utils/writeFileAndMkDir");
-
-const outputFile = path.join(__dirname, "../src/generated/plugins.js");
-
-console.log("Generating @babel/standalone files");
-
-let imports = "";
-let list = "";
-let allList = "";
-
-for (const plugin of pluginConfig) {
-  const camelPlugin = camelCase(plugin);
-  imports += `import ${camelPlugin} from "@babel/plugin-${plugin}";`;
-  list += `${camelPlugin},`;
-  allList += `"${plugin}": ${camelPlugin},`;
-}
-
-const fileContent = `
-/*
- * This file is auto-generated! Do not modify it directly.
- * To re-generate run 'make build'
- */
-${imports}
-
-export {${list}};
-
-export const all = {${allList}};
-`;
-
-writeFile(outputFile, format(fileContent, outputFile));
-console.log(`  ${chalk.green("✔")} Generated plugin list`);