chore: Migrate authentication to new tables (#1929)

This work provides a foundation for a more pluggable authentication system such as the one outlined in #1317.

closes #1317

app/models/Team.js

@@ -6,8 +6,6 @@ class Team extends BaseModel {
   id: string;
   name: string;
   avatarUrl: string;
-  slackConnected: boolean;
-  googleConnected: boolean;
   sharing: boolean;
   documentEmbeds: boolean;
   guestSignin: boolean;
@@ -17,11 +15,7 @@ class Team extends BaseModel {
 
   @computed
   get signinMethods(): string {
-    if (this.slackConnected && this.googleConnected) {
-      return "Slack or Google";
-    }
-    if (this.slackConnected) return "Slack";
-    return "Google";
+    return "SSO";
   }
 }