Add desktop notification duration preference to Account Settings

Description

From: http://mattermost.uservoice.com/forums/306457-general/suggestions/9182981-add-notification-persistence-preference-to-configu

Add a setting to control how long desktop notifications remain on screen.

1. Add to "Account Settings > Notifications" a setting called "Desktop notification duration".

2. Radio button options:

3 seconds
5 seconds
10 seconds
Unlimited

3. Help text: Choose how long you would like to see desktop notification messages after they first appear.

QA Test Steps

None

Status

Mana

8

Assignee

Joram Wilander

QA Assignee

None

Reporter

Ian Tien

Epic Link

None

Fix versions

None

Mattermost Team

None

Sprint

None

QA Testing Areas

None

GitHub Issue

None

Components

None
Configure