[KTable]: Shift + Tab navigation is trapped

[AlexVelezLl]

Product

Noticed in Kolibri learningequality/kolibri#12952.

Expected behavior

When I am already in the first cell of the table. Shift + Tab should have the default behaviour and focus the previous focusable element in the page.

Actual behavior

Right now, If the first cell of the headers, or if the first cell of the body have a checkbox (or probably any other focusable element inside), Shift + Tab is trapped between the cell and the checkbox inside, and we can't focus the previous focusable element outside of the table.

Compartir.pantalla.-.2025-01-09.16_27_37.mp4

Steps to reproduce the issue

1. Checkout Add quiz recipients selector as Side Panel kolibri#12952.
2. Go to Coach > Quiz > Create new Quiz > Select groups or individual learners recipients
3. Keyboard-navigate the Side Panel with Tab and Shift + Tab until you get to the learners table