Display error toast or dialog when sign in fails

[shobhitagarwal1612]

Current behavior:
Sign in request silent fails without any visible changes.

Expected behavior:
Show show some error toast or dialog message.

Note:
We only show a dialog if the sign in request fails due to permission denied error.

[gino-m]

I think a simple toast with "Sign in failed" is sufficient. Removing @rawbzz

[kenstershiro]

@shobhitagarwal1612 the uncovered case at the moment (sign in failing when it's not to do with permission denied) would be some sort of technical error like a timeout for example right? For setting the priority correctly I just wanted to be sure the most common case of incorrect credentials is already giving toast dialog.