Align retry safety for mutating connector operations across SDKs

## Description

Align the Python Connector SDK's retry safety contract with the Node.js SDK behavior introduced in [Azure/Connectors-NodeJS-SDK PR #91](https://github.com/Azure/Connectors-NodeJS-SDK/pull/91).

At `main` commit `d273862108d16615009572d730c12950be040a8c`, `ConnectorHttpClient._send_with_retry` retries every HTTP method for `429`, every `5xx` response, and `aiohttp.ClientError`. `ConnectorClientOptions` exposes retry counts and backoff settings but has no method-safety setting. A POST, PUT, PATCH, or DELETE connector action can therefore be submitted again after the service committed it but returned a transient response, or after an ambiguous transport failure.

The cross-language Connector SDK contract should be:

- Retry safe methods (`GET`, `HEAD`, `OPTIONS`, and `TRACE`) according to the configured retry policy.
- Do not automatically retry unsafe methods (`POST`, `PUT`, `PATCH`, and `DELETE`) by default.
- Provide an explicit, language-idiomatic per-client opt-in for applying the configured retry policy to unsafe methods, equivalent to Node.js `retryUnsafeHttpMethods`.
- Preserve the current retry-count, delay, timeout, and exponential-backoff options.

## Motivation

Connector operations include side-effecting actions such as sending messages and creating meetings, chats, channels, or files. Automatically replaying a completed action can duplicate customer-visible effects. This risk and the desired explicit opt-in are protocol-level concerns, not Node.js-specific behavior.

Consistent defaults across the .NET, Python, and Node.js Connector SDKs make client behavior predictable when customers move the same connector integration between languages.

## Acceptance criteria

- Add a `ConnectorClientOptions` setting with Python-idiomatic naming for opting unsafe HTTP methods into retries.
- Safe methods retain the configured retry behavior by default.
- Unsafe methods make one attempt by default for both transient HTTP responses and `aiohttp.ClientError` failures.
- Unsafe methods use the configured retry behavior when explicitly enabled.
- Add focused tests proving at least:
- a transient GET is retried;
- a transient POST is sent once by default;
- a transient POST is retried when explicitly enabled;
- PUT, PATCH, and DELETE follow the unsafe classification.
- Document the default and opt-in behavior in API documentation and release notes.
- Confirm whether implementation is confined to hand-written runtime/options code. Generated-client regeneration is not expected because generated clients use the shared `ConnectorHttpClient` and `ConnectorClientOptions` runtime surface.

## Related work

- Node.js implementation: [Azure/Connectors-NodeJS-SDK PR #91](https://github.com/Azure/Connectors-NodeJS-SDK/pull/91)
- .NET alignment: [Azure/Connectors-NET-SDK issue #269](https://github.com/Azure/Connectors-NET-SDK/issues/269)

从 ConnectorHttpClient._send_with_retry 和 ConnectorClientOptions 开始，然后检查现有的 retry 测试，以及生成的客户端所使用的共享 runtime/options 接口。为安全和不安全的方法添加有针对性的覆盖，包括 opt-in 路径，并更新 API 文档和发行说明，以记录默认行为和 opt-in 行为。

由索引模型根据 Issue 内容生成。