Move initialChunks store variable to window global variable

[ahce]

Summary

Supports calling loadableReady once, when there are multiple hydration entry points.

Example:

• main entry:

initSomething()

loadableReady(() => {
  window.dispatchEvent(new CustomEvent('loadable:ready'))
})

• app1 entry:

window.addEventListener('loadable:ready', () => {
  hydrateRoot(document.getElementById('app-1'), <App1 />)
})

• app2 entry:

window.addEventListener('loadable:ready', () => {
  hydrateRoot(document.getElementById('app-2'), <App2 />)
})

Note

To make this with the current version, the namespace property must be implemented for each entry with the loadableReady call, also the required chunks are duplicated for each JSON script when the different apps use the same component.

Test plan

No changes were applied that modify the current behavior.

[ahce]

Hi @theKashey , can you review this please? 🙏