Want to provide a way to query internal tasks

**Describe the feature you'd like**

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It is hoped that openmldb can be used internally to view the execution of internal tasks. For example, when batch sql is executed in an online environment, when the amount of data is large, the task usually takes a long time to execute. There is no way to view the status of the task, especially when the CLI is disconnected.

**Additional context**

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The issue requests a way to query internal task status, especially for long-running batch SQL jobs in an online environment. Look at the task execution and management code in the OpenMLDB backend. Identify where tasks are tracked and how their state is stored. Determine how to expose this state via a query interface, possibly through system tables or a new CLI command.

Written by the indexing model from the issue text.