Redis Sentinel SingeFlight: support of Redis master node username and password (#2039)

* Add support for Redis Username and Password configuration

Introduced Redis master authentication parameters (username and password) to the Redis Sentinel setup. This enhances compatibility with Redis environments that require authentication for both sentinel and master nodes.

* Add support for protected Redis Sentinel configuration and related unit tests

.github/workflows/ci.yml

@@ -34,6 +34,9 @@ jobs:
       REDIS_SENTINEL_TEST_MASTER_NAME: redis-1
       REDIS_SENTINEL_TEST_PASSWORD: sekret
       PROTECTED_REDIS_TEST_ENDPOINT: localhost:6380
+      PROTECTED_REDIS_TEST_USERNAME: default
+      REDIS_SENTINEL_TEST_PROTECTED_ENDPOINT: localhost:26380
+      REDIS_SENTINEL_TEST_PROTECTED_MASTER_NAME: protectedredis-1
       ATHENS_PROTECTED_REDIS_PASSWORD: AthensPass1
       GA_PULL_REQUEST: ${{github.event.number}}
     runs-on: ubuntu-latest
@@ -69,6 +72,17 @@ jobs:
         env:
           REDIS_PORT_NUMBER: 6380
           REDIS_PASSWORD: AthensPass1
+      redis-sentinel-protected-redis:
+        image: bitnami/redis-sentinel
+        env:
+          REDIS_MASTER_HOST: protectedredis
+          REDIS_MASTER_PORT_NUMBER: 6380
+          REDIS_MASTER_SET: protectedredis-1
+          REDIS_SENTINEL_PASSWORD: sekret
+          REDIS_SENTINEL_QUORUM: "1"
+          REDIS_SENTINEL_PORT_NUMBER: 26380
+        ports:
+          - 26380:26380
     steps:
       - uses: actions/checkout@v4
       - name: Set up Go