<mat-tab> Hide and Show Feature

#### Bug, feature request, or proposal:
hide/show behavior need to Provide in future release.

#### What is the expected behavior?

wanted to hide/show tab.
#### What is the current behavior?
currently you ppl are providing disabled feature so i wanted to hide/show tab.

#### What are the steps to reproduce?
provide api include hide/show feature.
#### What is the use-case or motivation for changing an existing behavior?
i need to show/hide tabs for that i need this feature instead of disabled api.

#### Which versions of Angular, Material, OS, TypeScript, browsers are affected?
i have used angular5 and Material design 5.2. please go through the below link for your reference.
https://material.angular.io/components/tabs/api

#### Is there anything else we should know?
apart from disable tab everything is working fine.

Issue にリンクされている Angular Material tabs API から始め、既存の無効化されたタブの動作を調査します。想定される非表示/表示のセマンティクスと、影響を受けるタブの実装およびテストを特定します。API と動作が明確に仕様化され、テストでカバーされた時点で作業は完了です。

索引モデルが issue の本文から書いたものです。