core: frontend: MAVLink routers: allow managing tlog generation

[ES-Alexander]

Current behaviour

The MAVLink Router and MAVLink Server routing options both automatically generate .tlog telemetry log files which uses space on the onboard computer for data that may be unnecessary, especially since telemetry logging is already often done by the control station software.

Expected or desired behaviour

There is existing discussion in #2328 for handling log removal on a full disk, but it would also be useful to have some control over the generation aspect of the pipeline, allowing

• at least to disable tlog generation entirely, but
• ideally also providing an option to only generate them while the vehicle is armed (like the existing LOG_DISARMED parameter for .bin log management in ArduPilot firmware), and
• potentially to start logging to a new file at
  • arm/disarm state changes (like the LOG_FILE_DSRM_ROT ArduPilot parameter), and/or
  • a max file size or logging duration (per this comment)

Additional Context

Issue suggested by @Williangalvani, together with the quote:

I'd only enable them for troubleshooting

Prerequisites

• I have checked to make sure that a similar request has not already been filed or fixed.