Allow passing --slow param to mocha in hardhat test

[samlaf]

the hardhat builtin test task: https://github.com/NomicFoundation/hardhat/blob/master/packages/hardhat-core/src/builtin-tasks/test.ts
doesn't seem to allow us passing arbitrary mocha arguments to mocha.
I personally really like calling mocha with --slow 0, which shows the time each test took (not only those considered slow by mocha).
It would be nice to either add this as a param to the hardhat test task, or otherwise to have this task read from .mocharc.json or some other mocha config file.

[github-actions]

This issue is also being tracked on Linear.

We use Linear to manage our development process, but we keep the conversations on Github.

LINEAR-ID: 18d30311-8352-4661-929e-1545b21dcbf0

[feuGeneA]

See also #2359

[github-actions]

This issue was marked as stale because it didn't have any activity in the last 30 days. If you think it's still relevant, please leave a comment indicating so. Otherwise, it will be closed in 7 days.

[github-actions]

This issue was closed because it has been stalled for 7 days with no activity.