Issue type

I'm submitting a ... (check one with "x")

• bug report
• feature request

Issue description

Current behavior:
For now, we have only NbLayoutDirectionService which provides information about a state of our layout. So, when we using ChangeDetectionStrategy.OnPush in component and wanna use layout service we have to trigger change detection manually or use async pipe, for example.

Expected behavior:
I want to suggest building two directives: nbIfRtl and nbIfLtr. Both this directives have to support 'else' syntax like ngIf.
This directive will help us create cleaner code without manually subscriptions management in each component which uses ChangeDetectionStrategy.OnPush and NbLayoutDirectionService.