lightning: save chunk checkpoint timely (#1080)

[ti-chi-bot]

This is an automated cherry-pick of #1080

What problem does this PR solve?

Try to save chunk checkpoint timely.

What is changed and how it works?

• Return a chunk status object when close chunk but it's not flushed. Then before each chunk restorer started, check and save all the pending chunk checkpoint if available.
• Try to save the chunk checkpoint before and after each deliver loop.

Check List

Tests

• Unit test
• Integration test

Code changes

• Has interface methods change

Side effects

• Possible performance regression
• Increased code complexity

Related changes

• Need to cherry-pick to the release branch
• Need to update the documentation

Release Note

• check and save chunk checkpoint timely.

[ti-chi-bot]

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[ti-chi-bot]

@ti-chi-bot: This cherry pick PR is for a release branch and has not yet been approved by release team.
Adding the do-not-merge/cherry-pick-not-approved label.

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