fix(reveal card): card shadow being cut off

[yggg]

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Short description of what this resolves:

Shadow from nb-card was cut off since it's container nb-reveal-card
has overflow: hidden.
This fix removes shadow from nb-card and adds it to nb-reveal-card.

Also there is small refactoring:

1. All nested ::ng-deep blocks merged into single one.
2. Use :host(.revealed) {...} instead of :host { &.revealed {...} }.