Export replicated merge tree partition to object storage

[arthurpassos]

Changelog category (leave one):

• New Feature

Changelog entry (a user-readable short description of the changes that goes to CHANGELOG.md):

Export replicated merge tree partition to object storage.

Documentation entry for user-facing changes

...

CI/CD Options

Exclude tests:

• Fast test
• Integration Tests
• Stateless tests
• Stateful tests
• Performance tests
• All with ASAN
• All with TSAN
• All with MSAN
• All with UBSAN
• All with Coverage
• All with Aarch64
• All Regression
• Disable CI Cache

Regression jobs to run:

• Fast suites (mostly <1h)
• Aggregate Functions (2h)
• Alter (1.5h)
• Benchmark (30m)
• ClickHouse Keeper (1h)
• Iceberg (2h)
• LDAP (1h)
• Parquet (1.5h)
• RBAC (1.5h)
• SSL Server (1h)
• S3 (2h)
• Tiered Storage (2h)

[github-actions]

Workflow [PR], commit [e2b221a]

[arthurpassos]

TODO list from the top of my head:

1. Keep parts alive (done, not tested)
2. Improve zk communication (batch calls mainly)
3. Cleanup the code
4. Setting for max_retry_count
5. Preserve context from the time of export partition call
6. Document the code and the feature
7. Check if replica is up to date enough
8. Local & per part exponential back-off?
9. exceptions directory in zookeeper (done)
10. system table for replicated partitions (done)
11. ability to kill an export (done)
12. Setting to overwrite existing zk task (done)

[arthurpassos]

@codex

[arthurpassos]

Closing in favor of pr with new design, hopefully that one sticks #1124