Add toast notification to handle errors when updating a destination

[ftianli-amzn]

Issue #, if available:

Description of changes:

Reason for the change:

When user have both permissions of cluster:admin/opendistro/alerting/destination/get and cluster:monitor/state, user can enter the Edit destination page.
There is no notifications to handle the backend errors, especially the permission error, when the user attempts to click the Update button in the Edit destination page.

Note:
When user only has cluster:admin/opendistro/alerting/destination/get permission, the Edit button is greyed out. It's not because the user don't have the permission to update destinations, but because the user don't have the permission to check the cluster setting, especially opendistro.alerting.destination.allow_list, thus no destinations is allowed for the user to edit.

After the change:
A toast notification shows up when there is an error from backend, especially the permission error, occurs when clicking the Update button.

Testing:
unit test result: (Actually there is no unit tests for the toast notifications😐)

Test Suites: 6 skipped, 83 passed, 83 of 89 total
Tests:       20 skipped, 385 passed, 405 total
Snapshots:   135 passed, 135 total
Time:        63.306 s
Ran all test suites.
✨  Done in 64.28s.

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.