feat: allow for providing params to ElectoralSystem test checks

[kylezs]

Pull Request

Checklist

Please conduct a thorough self-review before opening the PR.

• [x] I am confident that the code works.
• [x] I have written sufficient tests.
• [x] I have written and tested required migrations.
• [x] I have updated documentation where appropriate.

Summary

Allows us to avoid duplicating the "hook_called" etc. I'm also going to need to this to, for example, check how many elections are open at any one time, and would rather not write a hook specific to the number of times I expect, as it will change throughout the test.

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 56.66667% with 13 lines in your changes missing coverage. Please review.

Project coverage is 72%. Comparing base (f35c07f) to head (e47a139). Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
...allets/cf-elections/src/electoral_systems/mocks.rs	57%	13 Missing :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #5441 +/- ## ====================================== - Coverage 72% 72% -0% ====================================== Files 490 490 Lines 86916 86889 -27 Branches 86916 86889 -27 ====================================== - Hits 62395 62226 -169 - Misses 21587 21706 +119 - Partials 2934 2957 +23 ```

:umbrella: View full report in Codecov by Sentry.
:loudspeaker: Have feedback on the report? Share it here.

---

🚨 Try these New Features:

• Flaky Tests Detection - Detect and resolve failed and flaky tests
• JS Bundle Analysis - Avoid shipping oversized bundles