Make ToPickle a Generic

[hendrikmakait]

Extracted from #8096

• 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.

       18 files   -        2         18 suites   - 2   9h 30m 18s ⏱️ - 2h 5m 11s
  3 769 tests +     14    3 657 ✔️ +     14     109 💤 +    5  3 ❌  - 5 
31 400 runs   - 5 105  29 857 ✔️  - 4 973  1 540 💤  - 125  3 ❌  - 7 

For more details on these failures, see this check.

Results for commit 0d10798. ± Comparison against base commit 4f30abc.

This pull request removes 1 and adds 15 tests. Note that renamed tests count towards both.

distributed.tests.test_scheduler ‑ test_gather_bad_worker_removed

distributed.cli.tests.test_dask_worker.test_listen_address_ipv6[tcp:..[ ‑ 1]:---nanny]
distributed.cli.tests.test_dask_worker.test_listen_address_ipv6[tcp:..[ ‑ 1]:---no-nanny]
distributed.diagnostics.tests.test_memray
distributed.diagnostics.tests.test_memray ‑ test_basic_integration_scheduler
distributed.diagnostics.tests.test_memray ‑ test_basic_integration_scheduler_report_args[False]
distributed.diagnostics.tests.test_memray ‑ test_basic_integration_scheduler_report_args[report_args0]
distributed.diagnostics.tests.test_memray ‑ test_basic_integration_workers[1]
distributed.diagnostics.tests.test_memray ‑ test_basic_integration_workers[False]
distributed.diagnostics.tests.test_memray ‑ test_basic_integration_workers[True]
distributed.diagnostics.tests.test_memray ‑ test_basic_integration_workers_report_args[False]
…

♻️ This comment has been updated with latest results.

[crusaderky]

out of scope: fairly sure this method is redundant with __eq__

[hendrikmakait]

Good point, didn't even pay attention to this. Dropped __ne__ as a drive-by fix.

[crusaderky]

Good to merge as soon as CI finishes