[client-v2] Expose supported configuration options via a public API

Is your feature request related to a problem?

Connectors and tools built on top of the Java client (e.g. Kafka Connect sink, Spark connector, ingestion frameworks, config-validation UIs) need to know which configuration options the client supports so they can expose, validate, and document them programmatically. Today there is no supported API call to retrieve this list:

• ClientConfigProperties (client-v2) is a public enum, but it only carries the option key, value type, and default value — no human-readable description, no allowed-value/choices metadata, and no indication of whether an option is required or deprecated.
• jdbc-v2 implements Driver.getPropertyInfo(url, info) returning DriverPropertyInfo[], but that is JDBC-specific and not usable from plain client-v2.

Describe the solution you'd like

A public API on the client (e.g. Client.getSupportedOptions() or a static method on ClientConfigProperties) that returns structured metadata for every supported option:

• option key (e.g. connect_timeout)
• value type
• default value
• description
• allowed values / choices where applicable
• flags such as required, deprecated, sensitive (e.g. password, so tools know to mask it)

This would let integrators generate their config surface directly from the client instead of hard-coding option lists that drift out of date. Ideally jdbc-v2's getPropertyInfo would be backed by the same metadata source so the two stay consistent.

Describe alternatives you've considered

• Iterating ClientConfigProperties.values() via the enum — works for key/type/default but lacks descriptions and semantic metadata, and does not cover dynamic prefixes (clickhouse_setting_*, http_header_*).
• Scraping the docs — brittle and not machine-friendly.

从 client-v2 的 ClientConfigProperties enum 和 jdbc-v2 的 Driver.getPropertyInfo(url, info) 入口点开始，然后追踪当前键、类型和默认值是如何定义的。完成后应为 plain client-v2 提供结构化元数据，涵盖动态前缀和请求的 flags，并保持 JDBC 属性信息的一致性。