Changes to List SSH sessions

changed the pattern of the path request parameter machine_id from ^dm-[a-z0-9]([a-z0-9-]*[a-z0-9])?$ to ^dm-[0-9a-f]{8}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{12}$

for the path request parameter machine_id, the minLength was increased from 0 to 4

added the pattern ^dm-[a-z0-9]([a-z0-9-]*[a-z0-9])?$ to the path request parameter machine_id

for the path request parameter machine_id, the maxLength was set to 253

endpoint added