[Mm-7854] [Backend] Add an endpoint to revoke sessions from all users (#11200)

* first steps towards revoke all sessions endpoint

* route added

* change permission into a more restrictive one

* fix url

* add store code

* testing & mocking

* fixing what merge broke

* remove sessions without retrieving them

* flush sessions from cache

* stop going through sessions to revoke caches, not needed anymore

* add test, fix func name

* fix tests

* remove unneeded code

* [MM-7854]remove access tokens, move to users

* fix docstring

* [MM-7854] improve readability by using require

* [MM-7854] fix tests

* [MM-7854]fix comment

* [MM-7854]improve testing logic

store/sqlstore/oauth_store.go

@@ -239,6 +239,13 @@ func (as SqlOAuthStore) RemoveAccessData(token string) *model.AppError {
 	return nil
 }
 
+func (as SqlOAuthStore) RemoveAllAccessData() *model.AppError {
+	if _, err := as.GetMaster().Exec("DELETE FROM OAuthAccessData", map[string]interface{}{}); err != nil {
+		return model.NewAppError("SqlOAuthStore.RemoveAccessData", "store.sql_oauth.remove_access_data.app_error", nil, "err="+err.Error(), http.StatusInternalServerError)
+	}
+	return nil
+}
+
 func (as SqlOAuthStore) SaveAuthData(authData *model.AuthData) (*model.AuthData, *model.AppError) {
 	authData.PreSave()
 	if err := authData.IsValid(); err != nil {