refactor: add precise parameter types to Router test fixtures

[soccerlover29]

Description

Adds specific parameter types to 10 methods across the Router test fixtures and helper classes, replacing untyped parameters that PHPStan flagged as "no type specified." All changes are in test-only files. I tested it by running a full-project PHPStan scan and all the relevant tests.

Contributes to #7731 (PHPStan "no type specified" errors).

Checklist:

• Securely signed commits
• Component(s) with PHPDoc blocks, only if necessary or adds value (without duplication)
• Unit testing, with >80% coverage
• User guide updated
• Conforms to style guide

[paulbalandan]

Hi @soccerlover29 , instead of hand-editing the baseline files, could you run composer phpstan:baseline so that they get properly updated?

[soccerlover29]

The 2 failing lint checks (PHP 8.2 Lint with PHP CS Fixer / PHP 8.5 Lint with PHP CS Fixer) appear to be unrelated to this PR, since the reported violation is in tests/system/Validation/ValidationTest.php, which this PR doesn't touch.

I checked out a clean copy of develop (no changes from this PR) and ran the same check locally with PHP CS Fixer 3.95.18, and it passes with 0 violations. The CI run used 3.95.19. Looks like a formatting-rule change between those two patch versions is flagging code that was previously considered compliant, independent of anything in this diff.