Feat/371 view only user implementation using user_permissions (#381)

* https://github.com/jambonz/jambonz-api-server/issues/371

Implemented view_only permission feature

* calling prepare-permissions in create-test-db.js

* check if there is only 1 permission and if it is VIEW_ONLY then consider user as read-only user

* setting is_view_only flag for view user by userid

lib/models/user-permissions.js

@@ -0,0 +1,53 @@
+const Model = require('./model');
+const {promisePool} = require('../db');
+const sqlAll = `
+SELECT * from user_permissions
+`;
+const sqlByUserIdPermissionSid = `
+SELECT * from user_permissions where user_sid = ? and permission_sid = ?
+`;
+const sqlByUserId = `
+SELECT * from user_permissions where user_sid = ?
+`;
+
+class UserPermissions extends Model {
+  constructor() {
+    super();
+  }
+
+  static async retrieveAll() {
+    const [rows] = await promisePool.query(sqlAll);
+    return rows;
+  }
+
+  static async retrieveByUserIdPermissionSid(user_sid, permission_sid) {
+    const [rows] = await promisePool.query(sqlByUserIdPermissionSid, [user_sid, permission_sid]);
+    return rows;
+  }
+  static async retrieveByUserId(user_sid) {
+    const [rows] = await promisePool.query(sqlByUserId, [user_sid]);
+    return rows;
+  }
+
+}
+
+UserPermissions.table = 'user_permissions';
+UserPermissions.fields = [
+  {
+    name: 'user_permissions_sid',
+    type: 'string',
+    primaryKey: true
+  },
+  {
+    name: 'user_sid',
+    type: 'string',
+    required: true
+  },
+  {
+    name: 'permission_sid',
+    type: 'string',
+    required: true
+  }
+];
+
+module.exports = UserPermissions;