Switch to using provider-specific classes, when available

[byrro]

It turns out that the OAuth2 class does not work when the provider has an Arcade well-known configuration and the user creates a custom OAuth provider. In order to work with well-known providers and custom OAuth providers, we must use the provider-specific class (e.g. auth.Slack), instead of OAuth2(id="arcade-slack").

This PR updates the current starter tools with an OAuth provider that has a specific class in Arcade's auth module. The remaining tools that have OAuth requirement but no specific class available, we changed the id from arcade-{provider}to just {provider}.