PoA Leader Lock for Block Production (#3203)

## Linked Issues/PRs
<!-- List of related issues/PRs -->

## Description
<!-- List of detailed changes -->

The goal with this change is to allow multiple authority nodes to be
live without causing contention on who should produce the next block.

Introduced the `LeaderLeasePort`:
```rs
#[async_trait::async_trait]
pub trait LeaderLeasePort: Send + Sync {
    async fn can_produce_block(&self, height: BlockHeight) -> anyhow::Result<bool>;
    async fn release_lease(&self) -> anyhow::Result<()>;
}
```

Where each block producer can check if the lease is available before
producing a block. On shutdown, it will always release the lease as
well.

The implementation is `RedisLeaderLeaseAdapter`, where we use a lease on
a Redis server. The server can have its own ttl for the lease so if a
block producer dies before releasing the lease, it can still be grabbed
by the other producers :)

## Checklist
- [ ] Breaking changes are clearly marked as such in the PR description
and changelog
- [ ] New behavior is reflected in tests
- [ ] [The specification](https://github.com/FuelLabs/fuel-specs/)
matches the implemented behavior (link update PR if changes are needed)

### Before requesting review
- [ ] I have reviewed the code myself
- [ ] I have created follow-up issues caused by this PR and linked them
here

### After merging, notify other teams

[Add or remove entries as needed]

- [ ] [Rust SDK](https://github.com/FuelLabs/fuels-rs/)
- [ ] [Sway compiler](https://github.com/FuelLabs/sway/)
- [ ] [Platform
documentation](https://github.com/FuelLabs/devrel-requests/issues/new?assignees=&labels=new+request&projects=&template=NEW-REQUEST.yml&title=%5BRequest%5D%3A+)
(for out-of-organization contributors, the person merging the PR will do
this)
- [ ] Someone else?

---------

Co-authored-by: Green Baneling <XgreenX9999@gmail.com>

Author: MitchTurner

.changes/changed/3203.md

@@ -0,0 +1 @@
+Add lease port for PoA adapter to allow multiple producers to be live but only one leader.

.github/workflows/ci.yml

@@ -235,11 +235,44 @@ jobs:
       - name: Run integration tests for kms only
         run: cargo test -p fuel-core-tests --features aws-kms -- kms
 
+  leader-lock-integration-tests:
+    name: Leader Lock Integration Tests (w/Redis)
+    needs:
+      - lint-toml-files
+      - prevent-openssl
+      - rustfmt
+      - check-changelog
+    runs-on: buildjet-4vcpu-ubuntu-2204
+    timeout-minutes: 45
+    env:
+      RUSTFLAGS: -D warnings
+    steps:
+      - uses: actions/checkout@v4
+      - name: Install Rust
+        uses: dtolnay/rust-toolchain@master
+        with:
+          toolchain: ${{ env.RUST_VERSION }}
+      - name: Install Redis
+        run: |
+          sudo apt-get update
+          sudo apt-get install -y redis-server
+      - name: Start Redis
+        run: |
+          redis-server --daemonize yes
+          redis-cli ping
+      - name: Run leader lock integration tests
+        run: |
+          echo "REDIS_URL=${REDIS_URL:-redis://127.0.0.1:6379} REDIS_DB=${REDIS_DB:-0} LEADER_LOCK_KEY_PREFIX=${LEADER_LOCK_KEY_PREFIX:-<unset>}"
+          env | sort | grep -Ei 'REDIS|LEADER|LOCK|FUEL' || true
+          (timeout 90s redis-cli MONITOR | stdbuf -oL grep -E 'SELECT|SET|PEXPIRE|DEL|leader|lock' || true) &
+          cargo test --package fuel-core-tests --test integration_tests leader_lock --features leader_lock -- --test-threads=1 --nocapture
+
   verifications-complete:
     needs:
       - cargo-verifications
       - publish-crates-check
       - cargo-test-kms
+      - leader-lock-integration-tests
     runs-on: ubuntu-latest
     steps:
       - run: echo "pass"