Milvus Expr Executor

## Input

## Result

Parameter meaning: The `auth` parameter is etcd root path, and the `code` parameter is expr execution expression.
Injection object: Currently, the objects injected by expr include: `param`, `proxy`, `rootcoord`, `querycoord`, `datacoord`, `quernode`, `datanode`. You can use this tool to get the running value of the object.
Usage example: 1. Get a configuration: `param.CommonCfg.GracefulTime.GetValue()` 2. Get a property value in the proxy object: `proxy.address` 3. Determine whether a graph exists in the datanode: `datanode.flowgraphManager.HasFlowgraph("aaa")`
Limitations: 1. Variables cannot be modified. 2. Methods with non-basic type parameters cannot be executed. 3. Functions with multiple return values cannot be chained.