pre-v9.0.0 merge to include rate 3 in the modem sim, additional features and bug fixes for tdma

Breaking Changes

• removed override_test_plan_packet_duration rosparam from tdma_scripted_node. If a tdma test plan yaml is being used, the packet_duration_sec in the test plan will be used. If packet_duration_sec is not defined for any of the test cases, the default packet duration for the rates in that test will be used. If no test plan yaml is passed, the node will use the values passed at init.

New Features / Improvements

• Added rate 3 snr and probability numbers to the modem simulator (this is handled in the sim_packet_performance_node.py node).
• always_send_test_data rosparam now works liked the mircomodem2 ASD config param. In the ROS Tdma case, when always_send_test_data==True the tdma MAC will pad any remaining space in the mini (if any) then the dataframe with zeros. When no data is queued, the tdma MAC will generate a full packet of all zeros for mini and data frame bytes.

Bugfixes

• There was a bug in the logic for cycling the tests. If no data was sent in a given window it would still move to the next test. It's fixed now so we only move to the next test case if we actually transmitted a packet.