This change "collapses" together log "groups" containing hidden fields
for the TTY logger.
e.g. `actions.foo._a` and `actions.foo_b` will show up as a combined `actions.foo`.
Caveats: Since we don't know in advance how many tasks are in a group, the state will change back and forth.
For each task in a group, the state will transition from computing to complete (e.g. blue to green), then back to computing and so on.
The transition is fast enough not to be visibile.
Signed-off-by: Andrea Luzzardi <aluzzardi@gmail.com>