[Sidebar] should consider changes to responsive breakpoints even if they made afterward

### Issue type

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

* [ ] bug report
* [x] feature request

### Issue description

**Current behavior:**

**Expected behavior:**

- Sidebar: should consider changes to responsive breakpoints even if they made afterward
- responsive resets fixed sidebar state on compacted -> expanded state change (should respect default provided value)
**Steps to reproduce:**

**Related code:**

```
insert short code snippets here
```

### Other information:

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

```

**Angular, Nebular**
```

```