Add password support to Redis chat memory autoconfigure

[OneZero-Y]

Fixes #6621

Summary

Redis chat memory autoconfiguration supports host and port, but not password. Users with password-protected Redis instances had to provide their own RedisClient bean instead of using spring.ai.chat.memory.repository.redis.* properties.

This PR adds an optional password property and wires it into the Jedis RedisClient when configured. The legacy spring.ai.chat.memory.redis.* prefix continues to work via delegation.

Changes

• Add password to RedisChatMemoryRepositoryProperties
• Apply password when creating RedisClient in RedisChatMemoryRepositoryAutoConfiguration
• Delegate password in deprecated RedisChatMemoryProperties for the legacy prefix
• Document spring.ai.chat.memory.repository.redis.password in chat-memory.adoc
• Add unit tests for password binding with old and new property prefixes

Configuration

spring:
  ai:
    chat:
      memory:
        repository:
          redis:
            host: redis.example.com
            port: 6379
            password: ${REDIS_PASSWORD}

Legacy prefix (still supported):

spring:
  ai:
    chat:
      memory:
        redis:
          password: ${REDIS_PASSWORD}

Test plan

• ./mvnw -pl auto-configurations/models/chat/memory/spring-ai-autoconfigure-model-chat-memory-redis,auto-configurations/models/chat/memory/repository/spring-ai-autoconfigure-model-chat-memory-repository-redis -am test '-Dtest=RedisChatMemoryAutoConfigurationTests' -Dsurefire.failIfNoSpecifiedTests=false
• Password binds correctly via spring.ai.chat.memory.repository.redis.password
• Password binds correctly via legacy spring.ai.chat.memory.redis.password
• No password configured → existing behavior unchanged

[OneZero-Y]

Hey @dimitarproynov — would you mind taking a look when you get a chance? This adds optional password support to Redis chat memory autoconfigure (spring.ai.chat.memory.repository.redis.password), with the legacy spring.ai.chat.memory.redis.* prefix still delegated.