fetch() instrumentation compatibility with Nuxt.js and ofetch

[jackylamhk]

Nuxt.js uses ofetch for $fetch. However, when it initializes it creates a copy of window.fetch() so it won't use the patched version.

To patch the underlying window.$fetch to use the patched version, we need to re-initialize it after the agent is initialized:

vueApp.use(ApmVuePlugin, {
    config,
    router: useRouter(),
})
globalThis.$fetch = createFetch()