go/vault: Add simple consensus layer vault

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🔨 Latest commit	4a9f73a6e0325dc490b7ed994f0e39d0ea3920da
🔍 Latest deploy log	https://app.netlify.com/sites/oasisprotocol-oasis-core/deploys/663a055aefdb100008d09c19

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 54.29603% with 633 lines in your changes are missing coverage. Please review.

Project coverage is 64.96%. Comparing base (87ceaf9) to head (4a9f73a). Report is 3 commits behind head on master.

Files	Patch %	Lines
go/vault/api/grpc.go	16.04%	130 Missing and 6 partials :warning:
go/consensus/cometbft/vault/vault.go	31.94%	90 Missing and 8 partials :warning:
go/vault/api/action.go	40.25%	89 Missing and 3 partials :warning:
go/consensus/cometbft/apps/vault/transactions.go	68.34%	24 Missing and 20 partials :warning:
go/consensus/cometbft/apps/vault/state/state.go	72.30%	18 Missing and 18 partials :warning:
go/consensus/cometbft/apps/vault/messages.go	29.78%	26 Missing and 7 partials :warning:
go/vault/api/methods.go	21.42%	29 Missing and 4 partials :warning:
go/vault/api/vault.go	60.37%	19 Missing and 2 partials :warning:
go/consensus/cometbft/apps/vault/vault.go	69.49%	15 Missing and 3 partials :warning:
go/consensus/cometbft/apps/vault/genesis.go	65.95%	8 Missing and 8 partials :warning:
... and 17 more

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #5662 +/- ## ========================================== - Coverage 65.30% 64.96% -0.35% ========================================== Files 599 618 +19 Lines 61808 63166 +1358 ========================================== + Hits 40362 41034 +672 - Misses 16751 17318 +567 - Partials 4695 4814 +119 ```

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