Tabs Problem

### Issue type

**I'm submitting a ...**

* [x] bug report
* [ ] feature request
* [ ] question about the decisions made in the repository

### Issue description

**Current behavior:**
When we have lots of tabs in nb-tabset they will go out of container bounds

**Expected behavior:**
When we have lots of tabs I think user should see a scrollbar to scroll and see rest of tab handles, or maybe another way is to show a continue indicator at end and enable a dragger so user can drag and see rest of tab handles or at least extra items be listed under others.

**Steps to reproduce:**

**Related code:**

Simply can be reproduced by adding extra tabs to charts-panel component view of starter kit
```

```

### Other information:

**npm, node, OS, Browser**
```

```

**Angular, Nebular**
```
"@angular/core": "^9.0.4",
"@nebular/theme": "5.0.0",
```