The output of the `Module::output singleR` function is inconvenient to use when `reduce == false` in a multi-process environment

[goodchong]

Background

The module::output singleR function, when reduce == false in a multi-process environment, outputs a local indptr, not a global indptr, and therefore not a complete CSR format.
To use it externally, merging files from multiple processes into a single, complete CSR format, it needs to be converted.

Describe the solution you'd like

In this case, we should output the COO format directly for easier external matrix concatenation and use.

Task list only for developers

• Notice possible changes of behavior
• Explain the changes of codes in core modules of ESolver, HSolver, ElecState, Hamilt, Operator or Psi

Notice Possible Changes of Behavior (Reminder only for developers)

No response

Notice any changes of core modules (Reminder only for developers)

No response

Notice Possible Changes of Core Modules (Reminder only for developers)

No response

Additional Context

No response

Task list for Issue attackers (only for developers)

• Review and understand the proposed feature and its importance.
• Research on the existing solutions and relevant research articles/resources.
• Discuss with the team to evaluate the feasibility of implementing the feature.
• Create a design document outlining the proposed solution and implementation details.
• Get feedback from the team on the design document.
• Develop the feature following the agreed design.
• Write unit tests and integration tests for the feature.
• Update the documentation to include the new feature.
• Perform code review and address any issues.
• Merge the feature into the main branch.
• Monitor for any issues or bugs reported by users after the feature is released.
• Address any issues or bugs reported by users and continuously improve the feature.

[goodchong]

Only outputs val + col + indptr_local, without outputting any line mapping information.
Cannot reliably construct a global CSR.
Because indptr_local only tells you the start and end positions of the "i-th local line", but doesn't know the global line number corresponding to local line i.