refs: #6

The 'human' format is nice, but it make reading durations at glance
harder.

refs: #6

The Time Entries API doesn't have filtering options, so I am filtering
the response client side. Not great, we'll see if there are other
options.

refs: #6

The Rich's table has the option of adding a table footer. It adds an
additional row visually distinct from the data rows:

     $ tgl entries --project-id 178435728 group-by --field tags --start-date 2023-01-30

          Time Entries

     tags           Duration
     ─────────────────────────
     type:support   9:40
     type:meeting   7:38
     type:goal      5:58
     type:sync      5:08
     type:hr        0:54
     ─────────────────────────
     Total          29:20

refs: #6

Running timers have a negative duration that would impact totals.

We are now showing:

- tgl entries list
- tgl entries list --project-id 123
- tgl entries group-by --field tags

I should lower the maintenance cost of these tests!