fix(a11y): update role to radiogroup for radio group control (#1378)

## PR Checklist

Please check if your PR fulfills the following requirements:

- [ ] Tests for the changes have been added (for bug fixes / features)
- [ ] Docs have been added / updated (for bug fixes / features)
- [ ] If applicable, have a visual design approval

## PR Type

What kind of change does this PR introduce?

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- [x] Bugfix
- [ ] Feature
- [ ] Code style update (formatting, local variables)
- [ ] Refactoring (no functional changes, no api changes)
- [ ] Build related changes
- [ ] CI related changes
- [ ] Documentation content changes
- [ ] Other... Please describe:

## What is the current behavior?
The a11y role for the radiogroup control was set as `group`
<!-- Please describe the current behavior that you are modifying, or
link to a relevant issue. -->

Issue Number: CDE-1196

## What is the new behavior?
Based on discussions with the accessibility team, updated the role to
the more specific `radiogroup` role.

## Does this PR introduce a breaking change?

- [ ] Yes
- [x] No

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and migration path for existing applications below. -->

## Other information

Co-authored-by: Andrea Fernandes <andreaf1@vmware.com>

projects/angular/src/forms/radio/radio-container.ts

@@ -106,7 +106,7 @@ export class ClrRadioContainer extends ClrAbstractContainer implements AfterCont
  }
 
  private setAriaRoles() {
- this.role = this.radios.length ? 'group' : null;
+ this.role = this.radios.length ? 'radiogroup' : null;
  }
 
  private setAriaLabelledBy() {