feat: add environment lock (#116)

* Add Lock entity

* Add APIs for Lock

* Add lock validation in API and slack

* Add Lock tab

* Fix the document for the locking system

Author: Noah Hanjun Lee

docs/concepts/deployment.md

@@ -12,6 +12,6 @@ With approval, Gitploy waits until it matches the required approving approvals.
 
 Rollback is the best way to recover while you fix the problems. Gitploy supports the rollback, and you can choose one of the successful deployments to rollback. 
 
-For best practice, you should lock the repository to block deploying by others until finishing to fix the problems. Gitploy provide the 'lock' feature in UI and Chatops.
+For best practice, you should lock the environment to block deploying by others until finishing to fix the problems. Gitploy provide the 'lock' feature in UI and Chatops.
 
 *Note that if the ref of the selected deployment is a branch, Gitploy automatically references the commit SHA to prevent deploying the head of the branch.*

docs/concepts/permission.md

@@ -11,8 +11,8 @@ Here are capabilities for each permission:
 
 * **Read** - Users can read all activities that happened in the repository, such as deployments, approvals. And users are also capable of responding to the approval.
 
-* **Write** - Users can deploy and rollback for the `REF`. 
+* **Write** - Users can lock, deploy, and rollback for the `REF`. 
 
-* **Admin** - Users can configures the repository, such as activating and locking.
+* **Admin** - Users can configures the repository, such as activating.
 
 Of course, write and admin permission cover the ability of read permission.