fix(framework): copy "base" pkg i18n assets to dist/prod (#12072)

Recently added i18n texts to the `base` package are not properly shipped - the i18n assets are missing from `@ui5/webcomponents-base/dist/prod/generated/assets/i18n` folder, causing issues like:

> RollupError: Could not resolve "../assets/i18n/messagebundle_en.json"
> from "node_modules/@ui5/webcomponents-base/dist/prod/generated/json-imports/i18n.js"                                                                              

With this change, the assets are copied and present in dist/prod.

Author: ilhan007

packages/base/package-scripts.cjs

@@ -54,7 +54,7 @@ const scripts = {
 	generateProd: {
 		"default": "nps generateProd.remove-dev-mode generateProd.copy-prod",
 		"remove-dev-mode": `node "${LIB}/remove-dev-mode/remove-dev-mode.mjs"`,
-		"copy-prod": `copy-and-watch "dist/sap/**/*" dist/prod/sap/ && copy-and-watch "dist/thirdparty/preact/**/*.js" dist/prod/thirdparty/preact/`,
+		"copy-prod": `copy-and-watch "dist/sap/**/*" dist/prod/sap/ && copy-and-watch "dist/thirdparty/preact/**/*.js" dist/prod/thirdparty/preact/ && copy-and-watch "dist/generated/assets/**/*.json" dist/prod/generated/assets/`,
 	},
 	generateAPI: {
 		default: "nps generateAPI.generateCEM generateAPI.validateCEM",