fix: use unique ID for linked accounts (#3441)

- move OAuth-related fields off of api_keys into a new user_links table
- restrict users to single form of login
- process updates to user email/usernames for OIDC
- added a login_type column to users

coderd/httpmw/templateversionparam_test.go

@@ -53,6 +53,7 @@ func TestTemplateVersionParam(t *testing.T) {
 			HashedSecret: hashed[:],
 			LastUsed:     database.Now(),
 			ExpiresAt:    database.Now().Add(time.Minute),
+			LoginType:    database.LoginTypePassword,
 		})
 		require.NoError(t, err)