Add support of Angular 15

### Issue type

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

* [ ] bug report
* [x] feature request

### Issue description

Nebular has basic compatibility with Angular 15. Currently we must override the dependencies as follows:

```
{
"overrides": {
"@nebular/auth@9.1.0-rc.8": {
"@angular/animations": "15.0.1",
"@angular/cdk": "15.0.0",
"@angular/common": "15.0.1",
"@angular/core": "15.0.1",
"@angular/forms": "15.0.1",
"@angular/router": "15.0.1"
},
"@nebular/theme@9.1.0-rc.8": {
"@angular/animations": "15.0.1",
"@angular/cdk": "15.0.0",
"@angular/common": "15.0.1",
"@angular/core": "15.0.1",
"@angular/router": "15.0.1"
},
"@nebular/security@9.1.0-rc.8": {
"@angular/common": "15.0.1",
"@angular/core": "15.0.1",
"@angular/router": "15.0.1"
}
}
}
```