feat(login): dummy page for authentication

[abhigyantrips]

While we still work on the API side of things for authentication, we can go ahead with the frontend implementation so as to not block Noticeboard's development.

Authentication Flow:

1. The user clicks on a button that shows "Login with Outlook"
2. They are redirected to an API link (api.mitblr.club/...) which redirects them to Microsoft Authentication.
3. Once verified, the Access/Refresh tokens are returned to our endpoint, which in turn saves them and returns a JWT for the app to use.
4. Once returned, this JWT can be saved and utlized for all internal function calls.

Login Services (in services/):

1. login() - Redirect to API. Store the returned JWT to Shared Preferences.
2. validate(String jwt) - Validate the stored JWT against the API.

Login Controllers (in controllers/):

1. validateOnResume() - Initiate validation on resuming app usage.
2. validateOnStart() - Initiate validation on the app's first launch without a stored session. This function should be utilized while showing the user a splash screen on start.
3. logout() - Flush the previously stored JWT. Note that our logins are persistent until the JWT expires, and this function exists only in case the user wants to terminate their session (through a UI button).

Layout (Made in PowerPoint): (graphic design is my passion)

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