2.7: Buttons Radio with Reactive Forms example
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**Primary Actor**: User

**Scope**: Ngx-bootstrap DEMO / BS version 3&4

**Goal**: Show user example of radio buttons with ReactiveForms

Main success scenario:
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1. User opens Buttons demo page
2. User clicks on Radio with Reactive Forms sub-menu
3. User see button-group, which contain of 4 primary labeled buttons named as "A", "B", "C" and "Enable/Disable"
4. By default, 1st button is inactive, 2d - inactive, 3d - active and 4th - inactive
5. User able to click on each button
6. When user clicks on the 1st or 2d button, it become active and other buttons - inactive
7. When user clicks on the 4th button, it become active and other buttons - disabled
8. Component src should be written with usage of FormBuilder and FormGroup

Variations:
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2*. User scrolls to Radio with Reactive Forms sub-menu