improve progress reporting when installing snaps with dependencies

[Maciej Borzecki]

Reported in the forum: https://forum.snapcraft.io/t/snapd-papercuts-initiative/47263/8

When a snap pulls in additional dependencies e.g. through default-provider of a content slot, or a base that isn't installed yet, the progress visible to the user doesn't necessarily reflect that in an obvious way. What usually happens, is that the user is presented with auto-connecting prompt, while the tasks from a different lane are quietly progressing in the background.

[Maciej Borzecki (maciek-borzecki)]

Tracked internally in https://warthogs.atlassian.net/browse/SNAPDENG-35137

[林博仁(Buo-ren Lin) (brlin)]

I also have this issue: https://t.me/ubuntuzh/793817

If the message is changed to:

Automatically connecting _snap_ snap's snapd confinement interface plugs and sockets: _depending snap_...

it would be better.