Add Splash Screen

[Taliayaya]

Name	About	Title	Labels	Assignees
🚀 Feature Request	Creating a Splash screen for the redirected user	Add Splash Screen	enhancement	@Taliayaya

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Feature Request

Is your feature request related to a problem? Please describe.
While checking authentification, the user is redirected and can't tell whether he's already logged in or not. If the connection is slow, the effect is even worse.

Describe the solution you'd like
Creating a Splash Screen would tell the user that this is normal and he just has to wait.

Describe alternatives you've considered
Before redirecting, adding a pop up on the side of the screen to tell the user about the redirection. (With our beloved Mui)

Teachability, Documentation, Adoption, Migration Strategy
This will need setup a loading states that turns on before the redirection and while is on, show the loading status. No precise documentation is needed and it shouldn't need many changes.