5899 display a banner to alert users which need to reconnect their account (#6301)

Closes #5899

<img width="1280" alt="Index - banner"
src="https://github.com/twentyhq/twenty/assets/71827178/313cf20d-eb34-496a-8c7c-7589fbd55954">

---------

Co-authored-by: Charles Bochet <charles@twenty.com>

packages/twenty-server/src/modules/connected-account/services/accounts-to-reconnect.service.ts

@@ -0,0 +1,51 @@
+import { Injectable } from '@nestjs/common';
+
+import { UserVarsService } from 'src/engine/core-modules/user/user-vars/services/user-vars.service';
+import {
+  ConnectedAccountKeys,
+  ConnectedAccountKeyValueType,
+} from 'src/modules/connected-account/types/connected-account-key-value.type';
+
+@Injectable()
+export class AccountsToReconnectService {
+  constructor(
+    private readonly userVarsService: UserVarsService<ConnectedAccountKeyValueType>,
+  ) {}
+
+  public async removeAccountToReconnect(
+    userId: string,
+    workspaceId: string,
+    connectedAccountId: string,
+  ) {
+    const accountsToReconnect = await this.userVarsService.get({
+      userId,
+      workspaceId,
+      key: ConnectedAccountKeys.ACCOUNTS_TO_RECONNECT,
+    });
+
+    if (!accountsToReconnect) {
+      return;
+    }
+
+    const updatedAccountsToReconnect = accountsToReconnect.filter(
+      (id) => id !== connectedAccountId,
+    );
+
+    if (updatedAccountsToReconnect.length === 0) {
+      await this.userVarsService.delete({
+        userId,
+        workspaceId,
+        key: ConnectedAccountKeys.ACCOUNTS_TO_RECONNECT,
+      });
+
+      return;
+    }
+
+    await this.userVarsService.set({
+      userId,
+      workspaceId,
+      key: ConnectedAccountKeys.ACCOUNTS_TO_RECONNECT,
+      value: updatedAccountsToReconnect,
+    });
+  }
+}