remove unnecessary country reload (since default country is selected)

[Xygnite]

this pull request is intended to remove unnecessary country data reload in didUpdateWidget method, since country is already loaded in initState for its initialValue's isoCode is already loaded therefore the country is already 'pre-selected' and this made a strange behavior of the country is changing back into it's initialValue when i try to change the country selection here's some video of the behavior (was cropped because it's a private project but i hope you get the idea)

Pre patch behavior: https://user-images.githubusercontent.com/38610537/190352249-9c76d94f-e0be-4876-97e3-e436d8eb02c8.mp4

Post patch behavior: https://user-images.githubusercontent.com/38610537/190352344-fb17b17b-31cd-4ac2-9a6f-b64f61cf765e.mp4

Update: added prioritizedCountries to select custom prioritized countries