Add link to apps into UI

[AlexeyBarabash]

Description

Following up from #11204 .

Discussion is https://bravesoftware.slack.com/archives/C2HJYB45N/p1598556672031500 .

Now it is possible to reach apps page only by entering url brave://apps . When app are synced from one desktop to another, they arrive with gray state and it is required to click install on them.

In Google Chrome now link to apps is only displayed on the bookmarks bar and it is not in extensions settings page.

So to make apps be synced logically complete, need to return shortcut to apps into the hamburger menu and more tools section.