Sort raft snapshot related utils into different modules

[CalvinNeo]

What problem does this PR solve?

Issue Number: ref #7777 ref #4646

Problem Summary:

The pr is:

1. as part of kvstore refactor
2. as part of parallel pre-handling single snapshot
3. remove some needless utils
4. move some raft-related utils into these modules

We've done the following in this pr:

1. an PrehandleSnapshot.cpp which is about how to generate column format files(DTFiles) from SST format(including a whole rocksdb instance) file
2. an IngestSST.cpp which is about how to ingest an sst file as part of data of a region.
3. an ApplySnapshot.cpp is about how to replace data in a certain key range.

What is changed and how it works?

Check List

Tests

• Unit test
• Integration test
• Manual test (add detailed scripts or steps below)
• No code

Side effects

• Performance regression: Consumes more CPU
• Performance regression: Consumes more Memory
• Breaking backward compatibility

Documentation

• Affects user behaviors
• Contains syntax changes
• Contains variable changes
• Contains experimental features
• Changes MySQL compatibility

Release note

None

[CalvinNeo]

/run-all-tests

[JaySon-Huang]

LGTM with small comments

[CalvinNeo]

/run-all-tests

[ti-chi-bot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: JaySon-Huang, lidezhu

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[ti-chi-bot]

[LGTM Timeline notifier]

Timeline:

• 2023-09-18 03:51:21.231469445 +0000 UTC m=+489447.199057494: ☑️ agreed by JaySon-Huang.
• 2023-09-18 04:58:27.813773171 +0000 UTC m=+493473.781361222: ☑️ agreed by lidezhu.