fix(@react-aria/selection): don't mutate non-empty selection upon focus (#7513)
* fix(@react-aria/selection): don't mutate non-empty selection upon focus
closes #7512
* add some assertions
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Co-authored-by: GitHub <snowystinger@gmail.com>
Co-authored-by: Robert Snow <rsnow@adobe.com>
Co-authored-by: Reid Barber <reid@reidbarber.com>