Add similar whitespace escape logic to bash v2 completions than in other completions (#1743)

Signed-off-by: Toni Kangas <toni.kangas@upcloud.com>
Signed-off-by: Marc Khouzam <marc.khouzam@gmail.com>
Co-authored-by: Marc Khouzam <marc.khouzam@gmail.com>
Co-authored-by: Jeffrey Faer <jeffrey.faer@gmail.com>