VAULT: update state tracker now accounts for multiple epochs passing when advancing state enqueued withdrawn VRT

[coachchucksol]

To address H-02, Ive added the ability to shift the state of VRTs enqueued to withdraw - this mimics how the operators state is updated over multiple epochs.

Tests have also been added to cover this edgecase.

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 83.33333% with 4 lines in your changes missing coverage. Please review.

Project coverage is 82.51%. Comparing base (743a649) to head (968e0a1).

Files with missing lines	Patch %	Lines
restaking_core/src/config.rs	0.00%	4 Missing :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #124 +/- ## ========================================== - Coverage 82.54% 82.51% -0.04% ========================================== Files 86 86 Lines 8784 8788 +4 ========================================== Hits 7251 7251 - Misses 1533 1537 +4 ```

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[coachchucksol]

The error code I've added is because we want to use checked_div. There is no way to make the epoch_length 0, so this can never happen. However, to add some clarity to it, I made a config helper function that will calculate the epoch given a slot. I have also added some - cant-be-zero checks in the integration tests for future proofing.