Feat/redisvl integration tests

[rbs333]

This pr makes the following complete aggregation possible in RedisVL:

sql_str = """
    SELECT
        user,
        COUNT(age) as count_age,
        COUNT_DISTINCT(age) as count_distinct_age,
        MIN(age) as min_age,
        MAX(age) as max_age,
        AVG(age) as avg_age,
        STDEV(age) as std_age,
        FIRST_VALUE(age) as fist_value_age,
        ARRAY_AGG(age) as to_list_age,
        QUANTILE(age, 0.99) as quantile_age
    FROM user_simple
    GROUP BY credit_score
    """

sql_query = SQLQuery(sql_str)
redis_query = sql_query.redis_query_string(redis_url="redis://localhost:6379")
print("Resulting redis query: ", redis_query)
results = index.query(sql_query)
results

It adds support specifically for QUANTILE as well as fixes some parsing for STDEV, FIRST_VALUE, and ARRAY_AGG functionality. There was a bug where those were being added as apply statements instead of as reducers see: https://redis.slack.com/archives/C06R2N82D6E/p1769546814748909

[rbs333]

quantile takes 2 arguments instead of 1 like the others

[rbs333]

Add these to enable all available reducers from redis

[rbs333]

count reducer had a bug because unlike the rest of the reducers it takes 0 args