fix(RadioGroup): First item should be tabbable by default when none of the items selected

[sophieH29]

Fixes #1351

[DustyTheBot]

	Fails
🚫	Invalid entry format in CHANGELOG.md: >+- Fix `RadioGroup` first item should be tabbable by default when none of the items selected @sophieH29 ([#1515](https://github.com//pull/1515)) <

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[codecov]

Codecov Report

Merging #1515 into master will decrease coverage by 0.03%.
The diff coverage is 73.33%.

@@            Coverage Diff             @@
##           master    #1515      +/-   ##
==========================================
- Coverage   73.21%   73.17%   -0.04%     
==========================================
  Files         828      828              
  Lines        6212     6219       +7     
  Branches     1780     1784       +4     
==========================================
+ Hits         4548     4551       +3     
- Misses       1659     1663       +4     
  Partials        5        5

Impacted Files	Coverage Δ
...sibility/Behaviors/Radio/radioGroupItemBehavior.ts	100% <ø> (ø)	⬆️
...react/src/components/RadioGroup/RadioGroupItem.tsx	85.71% <62.5%> (-14.29%)	⬇️
...ges/react/src/components/RadioGroup/RadioGroup.tsx	92% <85.71%> (-1.48%)	⬇️

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[jurokapsiar]

The arrow navigation looks good.

Since now it is possible to focus unchecked item, we need to add support for Space bar as suggested by ARIA:

If the radio button with focus is not checked, changes the state to checked.
Otherwise, does nothing.
Note: The state where a radio is not checked only occurs on page load.