useLayoutEffect of <MenuPlacer /> component should listen for react-select's isLoading prop

Issue type: Bug

Issue recreation steps as follows,

1. Click on the dropdown field input. (Then we will get the "Loading" message. This is working as expected)
   

2. After the options are loaded into the dropdown, the menu doesn't get displayed above the field as it should. The menu does get rendered below the control.
   The menuPlacement prop "auto" is expected to kick-in in this state.
   

This is only happens once.

The issue is reproduceable in following code sandbox. (Be sure to click on the dropdown field of the page before the setTimeout timer)
https://codesandbox.io/s/strange-firefly-npzlhd?file=/src/App.js

Suggestion

I'm not sure whether this is feasible or not, but i think that we should perform the menu placement calculation after isLoading state has been set to true since that is an indicator that the options for the dropdown is completely loaded.

Affected react-select version: 5.7

Start with the component and its useLayoutEffect, then reproduce the behavior in the linked CodeSandbox using menuPlacement="auto" and a delayed isLoading change. Done means the menu placement is recalculated after loading finishes and the menu can appear above the field when appropriate; add or run the relevant placement tests if present.