[dvsim] Add control of max job submission per second
[dvsim] Add control of max job submission per second

default is up to 20 jobs per second
Signed-off-by: Weicai Yang <4fa8c7762ee4da95e3dee7dae2c3263ea16637f9@google.com>

lowRISC/opentitan,lowRISC/opentitan,lowRISC/opentitan,lowRISC/opentitan,lowRISC/opentitan,lowRISC/opentitan