Implement CLICKHOUSE_PASSWORD_FILE support in Docker image

Why it matters

This feature allows users to securely provide the ClickHouse password to the Docker container via a file, improving security by avoiding plain text passwords in environment variables.

How to use it

When running the ClickHouse Docker image, set the CLICKHOUSE_PASSWORD_FILE environment variable to the path of a file inside the container that contains the password. For example, use docker run -e CLICKHOUSE_PASSWORD_FILE=/path/to/password_file clickhouse/clickhouse-server.