Native slashing acct

[maurolacy]

Closes #129.

Proposed jailing API is tentative and can be changed / adjusted if needed.

Pre- vs. post-slashing behaviour of the delegated amounts (at the moment of the jailing handler call) must be established / defined based on on-chain checks, and / or analysis.

TODO:

• [x] Tests.

[codecov-commenter]

Codecov Report

Attention: 36 lines in your changes are missing coverage. Please review.

Comparison is base (c20eecc) 88.40% compared to head (a20d318) 88.50%. Report is 1 commits behind head on main.

Files	Patch %	Lines
contracts/provider/native-staking/src/contract.rs	79.41%	14 Missing and 7 partials :warning:
...ontracts/provider/external-staking/src/contract.rs	78.26%	2 Missing and 3 partials :warning:
...s/provider/native-staking/src/local_staking_api.rs	25.00%	0 Missing and 3 partials :warning:
...acts/provider/native-staking-proxy/src/contract.rs	87.50%	1 Missing and 1 partial :warning:
contracts/provider/vault/src/contract.rs	89.47%	0 Missing and 2 partials :warning:
...provider/external-staking/src/test_methods_impl.rs	50.00%	0 Missing and 1 partial :warning:
packages/apis/src/local_staking_api.rs	0.00%	1 Missing :warning:
packages/apis/src/vault_api.rs	93.75%	0 Missing and 1 partial :warning:

:exclamation: Your organization needs to install the Codecov GitHub app to enable full functionality.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #162 +/- ## ========================================== + Coverage 88.40% 88.50% +0.09% ========================================== Files 69 69 Lines 13151 13522 +371 Branches 13151 13522 +371 ========================================== + Hits 11626 11967 +341 - Misses 992 1011 +19 - Partials 533 544 +11 ```

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

[maurolacy]

Merging this, as it's in good shape already. We can always revisit / adjust the API later if needed.