Provide more configurable parsing of p4 monitor show output

Allow the option to group max command time by groups of commands, e.g. sync/transmit are expected to often run for a long time, whereas other commands are more surprising if running long (and thus deserve to be monitored more closely).

Updates to the config file might include command regexes and the group name, e.g.

```[yaml]
- commands:  "sync|transmit"
   group: sync_transmit
```