ui: Improve progress reporting on pins

when you provide --progress to ```ipfs pin add```, you get the following updates:
```
$ ipfs pin add --progress /ipns/hpkg.haiku-os.org
Fetched/Processed 8353 nodes
.
Fetched/Processed 8540 nodes
```
If ```ipfs pin add``` is unable to find a chunk, it just sits indefinitely waiting for it.

Just sitting at "Fetched/Processed 8353 nodes" leaves the user with a mystery of what's happening.
I've never seen IPFS want more than 10 or 15 chunks at a time, so there must be a limit on number of lines needed.

Docker does something similar in breaking container images intro chunks... maybe this UI could use some improvement? Here's an example:

obviously showing every CID isn't realistic, but showing the CID's that are in an active "want" state would be a great way to show activity.

The user is already asking for "verbose" information on what's happening via ```--progress```, it feels like IPFS could be providing a lot more information on what it's doing. (searching, downloading, etc)

Start at the `ipfs pin add --progress` command entry point and review how its current progress updates are produced. Define a bounded progress display that makes stalled or active chunk retrieval visible without listing every CID, then verify the command reports useful activity while pinning content.

Written by the indexing model from the issue text.