Fixing issue with UI and state being out of sync with checkboxes

fixes: CNVS-15785

test plan:
  - Go to New Files
  - Place cursor in "Search for files" input (this is for convenience)
  - Use `tab` key until the checkbox shows up for the first file in the list (about 11 key presses)
  - Checkbox should activate by either clicking with mouse, or pressing `spacebar`
  - Checkbox should be checked

Change-Id: Ib5e68f78b0813ff54954ad3d7109a076e27e1c37
Reviewed-on: https://gerrit.instructure.com/46256
Reviewed-by: Dan Minkevitch <dan@instructure.com>
Tested-by: Jenkins <jenkins@instructure.com>
QA-Review: Derek Hansen <dhansen@instructure.com>
Product-Review: Clay Diffrient <cdiffrient@instructure.com>