Add VmClient.operate

[olethanh]

Variation on perform_operation that allow a raw response. Move from the aleph-client code introduced in aleph-im/aleph-client#304

[github-actions]

Explanation:

The diff contains extensive changes that potentially introduce bugs or require deep understanding of the project architecture. Here are the highlights:

1. New Method operate: The addition of a new method operate introduces a significant change to the existing codebase. This method is complex and involves multiple asynchronous operations, authentication, and HTTP requests.

2. Dependencies and Imports: The addition of aiohttp.client._RequestContextManager and other imports suggests that this method is designed to handle asynchronous HTTP requests with context management, which could have broader implications for how the SDK interacts with external services.

3. Authentication and Request Handling: The method includes detailed steps for generating authentication headers and making authenticated requests. This level of detail and complexity could lead to potential bugs if not implemented correctly.

4. Potential Impact: The method is asynchronous and uses context managers, which could affect how other parts of the codebase interact with network operations. This could potentially impact the stability and performance of the SDK.

Given these factors, the PR is categorized as 'BLACK' due to the extensive changes and the potential for introducing bugs or requiring deep understanding of the project architecture. This level of complexity typically requires a high level of expertise and careful review.

[philogicae]

LGTM