feat: add a bunch of new Nebular demos (#1911)

src/app/pages/extra-components/stepper/stepper.component.ts

@@ -0,0 +1,43 @@
+import { Component, OnInit } from '@angular/core';
+import { FormBuilder, FormGroup, Validators } from '@angular/forms';
+
+@Component({
+  selector: 'ngx-stepper',
+  templateUrl: 'stepper.component.html',
+  styleUrls: ['stepper.component.scss'],
+})
+export class StepperComponent implements OnInit {
+
+  firstForm: FormGroup;
+  secondForm: FormGroup;
+  thirdForm: FormGroup;
+
+  constructor(private fb: FormBuilder) {
+  }
+
+  ngOnInit() {
+    this.firstForm = this.fb.group({
+      firstCtrl: ['', Validators.required],
+    });
+
+    this.secondForm = this.fb.group({
+      secondCtrl: ['', Validators.required],
+    });
+
+    this.thirdForm = this.fb.group({
+      thirdCtrl: ['', Validators.required],
+    });
+  }
+
+  onFirstSubmit() {
+    this.firstForm.markAsDirty();
+  }
+
+  onSecondSubmit() {
+    this.secondForm.markAsDirty();
+  }
+
+  onThirdSubmit() {
+    this.thirdForm.markAsDirty();
+  }
+}