Account List in Settings

[Sjmarf]

• Adds the Account List to the settings tab.
• Re-implemented AvatarView, AvatarBannerView and AvatarStackView.
• Added extensions to NavigationLink for shorter syntax when navigating to a NavigationPage.
• Fixed signing-out of accounts.

Related to #941

[EricBAndrews]

Code looks good, a couple nits related to CONTRIBUTING updates.

I also get a couple of compilation errors due to read and saved still being isRead and isSaved (FeedsView:113, Interactable2Providing+Extensions:21).

[EricBAndrews]

Looking good! I've noticed a couple very slight rough edges while testing:

• Signing out of an account that you are not currently logged into from the quick-switcher closes the switcher
• Signing out of the current account puts the app into guest mode--is this intentional? Discussion raised in Slack
• "Enter Guest Mode" is still available in the switcher even when you're already in Guest Mode--on this note, the switcher should probably have an active indication that guest mode is active, as it may appear broken for there to be no green active account indicator

[Sjmarf]

Signing out of an account that you are not currently logged into from the quick-switcher closes the switcher

Fixed 👍

"Enter Guest Mode" is still available in the switcher even when you're already in Guest Mode--on this note, the switcher should probably have an active indication that guest mode is active, as it may appear broken for there to be no green active account indicator

This button is temporary for testing purposes - in future we'll let the user add multiple different guest accounts to a section below the list of accounts. I'll make it obvious when you're signed into a guest account once that's done.

[EricBAndrews]

Nice! 🚀