Network occupancy dashboard

[gjoseph92]

Displays network occupancy in a lighter shade, CPU darker on the occupancy dashboard:

The tick mark seem broken (values wrap around at 1000ms), but they're also broken on main. I don't know enough bokeh to know why.

Currently includes #7020; will rebase once that's merged.

• Tests added / passed
• Passes pre-commit run --all-files

[github-actions]

Unit Test Results

See test report for an extended history of previous test failures. This is useful for diagnosing flaky tests.

       15 files  ±  0         15 suites  ±0   6h 19m 28s ⏱️ - 3m 25s
  3 101 tests  -   2    3 010 ✔️ +  2    84 💤  -   4    7 ❌ ±  0 
22 953 runs  +43  22 008 ✔️ +31  905 💤  - 21  40 ❌ +33 

For more details on these failures, see this check.

Results for commit 7c15569. ± Comparison against base commit 737913a.

[fjetter]

There are some genuine test failures

  File "/Users/runner/work/distributed/distributed/distributed/dashboard/components/scheduler.py", line 4154, in status_doc
    occupancy.update()
  File "/Users/runner/miniconda3/envs/dask-distributed/lib/python3.8/site-packages/bokeh/core/property/validation.py", line 95, in func
    return input_function(*args, **kwargs)
  File "/Users/runner/work/distributed/distributed/distributed/utils.py", line 748, in wrapper
    return func(*args, **kwargs)
  File "/Users/runner/work/distributed/distributed/distributed/dashboard/components/scheduler.py", line 173, in update
    occupancy_network, occupancy_cpu = zip(
ValueError: not enough values to unpack (expected 2, got 0)

Love the new/updated component!