设计可扩展的"查看器/蓝图命令"方法

EDIT: Most of this issue has been subsumed by RR-5659 We have a desire to trigger certain actions from our SDK that affects the viewer directly: * Activate blueprint $ID * Open/close recording $ID * Play/pause/move time Cursor * … So far, only a few of these have been implemented, and in rather ad-hoc ways: * https://GitHub.com/rerun-io/rerun/pull/8809/files * https://GitHub.com/rerun-io/rerun/blob/026d84622c054de3159646667a9d35c90e361e9f/crates/store/re_protos/proto/rerun/v0/log_msg.proto#L16-L17 ## Where can we send these commands? * From the logging SDKs (Python, Rust, C++) * From Python notebooks (via logging SDK) * From JS API? ### Blueprint changes Some of these commands can be encoded as changes to the blueprint store. This includes setting the time state, once this is part of the blueprint. Changes to blueprint can be implemented as any other store changes, i.e. by pushing a chunk (recordbatch). Similarly, querying the blueprint state ("what is the time Cursor at?") can be implemented as a data query. ## Design None yet, but it would be nice with something data driven, e.g. a protobuf definition of all commands as an oneof. ## Related issues * https://GitHub.com/rerun-io/rerun/issues/7728 * https://GitHub.com/rerun-io/rerun/issues/8318 * RR-5659