[Feature]: Support Flow cancel

[Emin017]

Self checks

• I have searched existing issues, including closed issues.
• I have read the documentation and development guide.
• This is a feature request, not a bug report or usage question.
• I have described the workflow need before proposing a solution.

Affected area

Flow/runtime

Problem or workflow need

Ecc should support flow cancel, which can save the current flow state and exit safely.

Proposed solution

We should add cancel command in ecc, and export this to rpc server for ecos-studio.

Alternatives considered

No response

Examples, command sketches, or references

No response

Are you willing to contribute this feature?

Yes, I can submit a PR.

Additional context

No response

[ZhishengZeng]

谁在做这个？

[Emin017]

谁在做这个？

Due to ECC integrating EDA tools via Python import, this feature is currently not feasible.