Components: [Tabs] Prevent user from activating/deactivating tabs

[Daeluse]

Bug, feature request, or proposal:

Feature Request

What is the expected behavior?

Following a similar function to how canActivate and canDeactivate works on Routing, it would be extremely beneficial to have a way to run a check before allowing a tab to be activated or deactivated.

What is the use-case or motivation for changing an existing behavior?

Within the tabs, if a user is able to change a setting or edit information and the user is required to click 'save' before the changes are committed, there should be a way to prompt the user of the existing changes before they can navigate away, by switching tabs or routes. The necessity here would be that we would need a way to check both on tab switch and route switch without (hopefully) having to duplicate code.

[PhilHuot]

Would be really nice to have.