when click mat-select input focus another input

#### Reproduction

Hi guys. I use ionic 4 and integrated angular material into my projects. Everything work perfectly but when I want to create the custom select component with search input I seem this issue. When open mat-select and click search input application focused another input. I don't solve this problem. I don't know maybe it's a bug. I upload *.gif file for more detail.

#### My Codes

```

```

Custom **mat-select** component:
```

{{label | translate}}

#### Screen


#### My Packages
```

`"@angular/animations": "8.2.14",
"@angular/cdk": "8.2.3",
"@angular/common": "8.2.14",
"@angular/core": "8.2.14",
"@angular/forms": "8.2.14",
"@angular/material": "8.2.3",
"@angular/platform-browser": "8.2.14",
"@angular/platform-browser-dynamic": "8.2.14",
"@angular/router": "8.2.14",
"@ionic-native/core": "5.17.1",
"@ionic-native/file": "5.17.1",
"@ionic-native/file-opener": "5.17.1",
"@ionic-native/file-transfer": "5.17.1",
"@ionic-native/in-app-browser": "^5.18.0",
"@ionic-native/keyboard": "^5.19.0",
"@ionic-native/network": "^5.18.0",
"@ionic-native/onesignal": "^5.18.0",
"@ionic-native/splash-screen": "5.17.1",
"@ionic-native/status-bar": "5.17.1",
"@ionic/angular": "4.11.5",
"@ionic/storage": "^2.2.0",`

```

まず、issue に示されているカスタム mat-select テンプレートとフォームのマークアップを使って動作を再現し、埋め込まれた検索入力ともう一方のフォーム入力に注目します。開くときと入力をクリックしたときの mat-select のフォーカス処理を追跡します。検索入力がフォーカスを受け取り、別の入力へフォーカスが移動せず、一覧にある Angular Material のバージョンに対して再現結果が検証されれば完了です。

索引モデルが issue の本文から書いたものです。