Synchronizer: Add --skip-catalog-sync flag for DR-oriented syncs

[saidixith002]

Summary

Adds a --skip-catalog-sync flag to sync-polaris that skips creation, overwrite, and removal of catalog objects on the target, while still synchronizing catalog-roles and
grants for catalogs that already exist there.

This complements the existing --skip-iceberg-content flag (added in #256) and is aimed at the same class of problem: disaster-recovery setups where the synchronizer
shouldn't be allowed to mutate certain top-level resources on the target.

Motivation

In a DR setup, target catalogs are often pre-created with intentionally different storage locations (allowedLocations, default-base-location, roleArn, etc.) than the
source. Today, if a catalog exists on both source and target and the synchronization strategy is CREATE_AND_OVERWRITE or REPLICATE (or --diff-only detects a
difference), the synchronizer will dropCatalogCascade + createCatalog on the target, copying the source catalog's storage config verbatim and silently clobbering the
DR-specific location.

--skip-catalog-sync lets operators keep principal, principal-role, catalog-role, and grant synchronization fully active while guaranteeing catalog objects themselves are
never created, overwritten, or removed on the target.

Changes

• PolarisSynchronizer: new skipCatalogSync constructor parameter/field. syncCatalogs() now checks this flag before each of the create/overwrite/remove operations.
• SyncPolarisCommand: new --skip-catalog-sync CLI option, wired into the PolarisSynchronizer constructor call.

Behavior when --skip-catalog-sync is set

• Catalogs that only exist on the source (would be created): skipped entirely, with a warning logged. Since no matching catalog exists on the target, there is nothing to
  synchronize catalog-roles/grants against, so these are also excluded from catalog-role sync for that catalog.
• Catalogs that exist on both source and target (would be overwritten): the catalog object itself (drop + recreate) is skipped, but catalog-roles and grants are still
  synchronized against the existing target catalog.
• Catalogs that would be removed (target-only, under the REPLICATE strategy): removal is skipped, and the target catalog is left untouched.

Iceberg namespace/table sync is governed independently by --skip-iceberg-content, so the two flags can be combined to synchronize only principals, principal-roles,
catalog-roles, and grants, without ever touching catalog objects or Iceberg content on the target.

Backward compatibility

--skip-catalog-sync defaults to false. No behavior changes for existing invocations unless the flag is explicitly passed.

Testing

Added PolarisSynchronizerSkipCatalogSyncTest, covering the skipped case (create/overwrite/remove all skipped on the target, source-only catalogs excluded from catalog-role
sync, catalogs existing on both sides still get catalog-role sync) and the non-skipped case (existing behavior unchanged). Updated PolarisSynchronizerSkipIcebergContentTest
call sites for the new constructor parameter; all existing tests continue to pass.