Refactor Connection Sparsity

[ben9809]

This pull request introduces an extension to calculate the connection sparsity of the model.

From now on, it is possible to calculate the connection sparsity even though the model doesn't have layers supported by the documentation list.

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 65.36%. Comparing base (4d19a3d) to head (8062ad1). Report is 2 commits behind head on dev.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## dev #240 +/- ## ========================================== + Coverage 64.69% 65.36% +0.67% ========================================== Files 16 16 Lines 796 745 -51 Branches 161 147 -14 ========================================== - Hits 515 487 -28 + Misses 239 221 -18 + Partials 42 37 -5 ``` | [Flag](https://app.codecov.io/gh/NeuroBench/neurobench/pull/240/flags?src=pr&el=flags&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=NeuroBench) | Coverage Δ | | |---|---|---| | [unittests](https://app.codecov.io/gh/NeuroBench/neurobench/pull/240/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=NeuroBench) | `65.36% <100.00%> (+0.67%)` | :arrow_up: | Flags with carried forward coverage won't be shown. [Click here](https://docs.codecov.io/docs/carryforward-flags?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=NeuroBench#carryforward-flags-in-the-pull-request-comment) to find out more.

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[jasonlyik]

Also consider the biases, like in RNN. And should track parameters named with 'bias'