SDKS-3064 | Add support for snapshot capabilities in Proxy mode

[sarrubia]

Split Synchronizer

What did you accomplish?

Add support for snapshot capabilities in Proxy mode

• SDKS-3065 cli flag -proxy-snapshot to be compatible with current -proxy-mmap-path
• SDKS-3066 Add endpoint to export hot snapshot from Admin server when proxy mode is enabled
• SDKS-3067 Let proxy starts with a snapshot without exiting on sync tasks failures
• SDKS-3077 Snapshot versioning support

How do we test the changes introduced in this PR?

1. Run an instance of Split proxy
2. Download the snapshot curl http://localhost:3010/admin/proxy/snapshot --output split.proxy.snapshot
3. Run a different instance of Split Proxy with the downloaded snapshot: split-synchronizer -proxy -proxy-snapshot "split.proxy.snapshot"

[mredolatti]

Implemented in another branch -- discarding