TF-1861 Add adr to use work manager

(cherry picked from commit 0a1c659327d74bc0b9c50fe2b2b1e7d3f3fcd1ae)

docs/adr/0026-fix-horizontal-scroll-bar-in-email-detail-view.md

@@ -1,4 +1,4 @@
-# 25. Hide Horizontal scroll bar in Email detail view
+# 26. Hide Horizontal scroll bar in Email detail view
 
 Date: 2023-04-24
 

docs/adr/0027-use-tuplekey-store-data-cache.md

@@ -1,4 +1,4 @@
-# 5. Use TupleKey store data cache
+# 27. Use TupleKey store data cache
 
 Date: 2023-04-27
 

docs/adr/0028-use-work-manager-to-mange-task-scheduling.md

@@ -0,0 +1,94 @@
+# 28. Use WorkManager to manage task scheduling
+
+Date: 2023-05-23
+
+## Status
+
+Accepted
+
+## Context
+
+- To automatically manage and schedule tasks. 
+- For example, automatically add email sending when network outage to `Queue` and automatically sending when network is back.
+
+## Decision
+
+- Use library `workmanager` on [pub.dev](https://pub.dev/packages/workmanager)
+
+### 1. Configuration
+
+- Add to `pubspec.yaml`
+```
+dependencies:
+  workmanager: ^0.5.1
+```
+
+- Setup on Android: [ANDROID_SETUP.md](https://github.com/fluttercommunity/flutter_workmanager/blob/main/ANDROID_SETUP.md)
+
+- Setup on iOS: [IOS_SETUP.md](https://github.com/fluttercommunity/flutter_workmanager/blob/main/IOS_SETUP.md)
+
+### 2. Implement
+
+- Initialize the WorkManager
+
+```
+await WorkManagerConfig().initialize();
+```
+
+- Create new `Worker`
+```
+final worker = Worker(
+  id: String // Task identifier
+  type: String // Job type, used to group jobs with the same purpose (Like Insert, Delete, Sent)
+  data: Map<String, dynamic> // Input parameters. Valid value types are: int, bool, double, String and their list
+);
+```
+
+- Create new `WorkRequest`
+
++ For non-repeating work: 
+```
+final workReuest = OneTimeWorkRequest(
+  worker
+  Duration? initialDelay,
+  Duration? backoffPolicyDelay,
+  ExistingWorkPolicy? existingWorkPolicy,
+  BackoffPolicy? backoffPolicy,
+  OutOfQuotaPolicy? outOfQuotaPolicy,
+  Constraints? constraints
+);
+```
++ For repeating work:
+```
+final workReuest = PeriodicWorkRequest(
+  worker
+  Duration? frequency,
+  Duration? initialDelay,
+  Duration? backoffPolicyDelay,
+  ExistingWorkPolicy? existingWorkPolicy,
+  BackoffPolicy? backoffPolicy,
+  OutOfQuotaPolicy? outOfQuotaPolicy,
+  Constraints? constraints
+);
+```
+
+- Add to `enqueue`
+
+```
+await WorkSchedulerController().enqueue(workReuest);
+```
+
+- Handle task in `handleBackgroundTask` method
+- To cancel task in WorkManager
+```
+await WorkSchedulerController().cancelByWorkType(workType);
+
+await WorkSchedulerController().cancelByUniqueId(uniqueId);
+
+await WorkSchedulerController().cancelAll();
+```
+
+
+## Consequences
+
+- The correct `mailbox` and `email` lists are obtained for each account