safekeeper: consider partial uploads when pulling timeline

[VladLazar]

Problem:

The control file contains the id of the safekeeper that uploaded it.
Previously, when sending a snapshot of the control file to another sk,
it would eventually be gc-ed by the receiving sk. This is incorrect
because the original sk might still need it later.

Summary of Changes:

When sending a snapshot and the control file contains an uploaded
segment:

• Create a copy of the segment in s3 with the destination sk in the
  object name
• Tweak the streamed control file to point to the object create in the
  previous step

Note that the snapshot endpoint now has to know the id of the requestor,
so the api has been extended to include the node if of the destination
sk.

Closes #8542

Checklist before requesting a review

• I have performed a self-review of my code.
• If it is a core feature, I have added thorough tests.
• Do we need to implement analytics? if so did you add the relevant metrics to the dashboard?
• If this PR requires public announcement, mark it with /release-notes label and add several sentences in this section.

Checklist before merging

• Do not forget to reformat commit message to not include the above checklist

[github-actions]

2160 tests run: 2091 passed, 0 failed, 69 skipped (full report)

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Code coverage* (full report)

• functions: 32.4% (7200 of 22251 functions)
• lines: 50.3% (58230 of 115676 lines)

* collected from Rust tests only

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_{The comment gets automatically updated with the latest test results
8f88330 at 2024-08-14T17:15:23.486Z :recycle:}

[petuhovskiy]

Looks good, can be merged after a few fixes

[arssher]

Thanks! LGTM.