Prevent modifying old snapshots in Iceberg

[homar]

Description

Is this change a fix, improvement, new feature, refactoring, or other?
fix
Is this a change to the core query engine, a connector, client library, or the SPI interfaces? (be specific)
iceberg connector
How would you describe this change to a non-technical end user or system administrator?
it prevents users from doing things which outcome is not obvious

Related issues, pull requests, and links

Fixes #12860

Documentation

(x) No documentation is needed.
( ) Sufficient documentation is included in this PR.
( ) Documentation PR is available with #prnumber.
( ) Documentation issue #issuenumber is filed, and can be handled later.

Release notes

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( ) Release notes entries required with the following suggested text:

# Iceberg
* Prevent modifying old snapshots. ({issue}`12860`)

[homar]

@ebyhr comments fixed, scope changed ;)

[ebyhr]

Merged, thanks!

[ebyhr]

@homar I think we should also block metadata modification (e.g. ADD COLUMN) for old snapshots. Could you send another PR if it makes sense?

[findinpath]

we should also block metadata modification (e.g. ADD COLUMN) for old snapshots.

There are multiple DDL changes that should be taken into account for blocking snapshots.

cc @findepi @electrum

[homar]

@homar I think we should also block metadata modification (e.g. ADD COLUMN) for old snapshots. Could you send another PR if it makes sense?

Sure I will, but I am not sure what else to block. Add column, changes in partitioning, what else ?