[python] Support tag rename and replace in the CLI

[Stephen0421]

Purpose

Add paimon tag rename and paimon tag replace for filesystem catalogs, and let paimon tag create set a retention.

Filesystem catalogs delegate to the existing FileStoreTable.rename_tag and replace_tag. A missing tag or a conflicting new name becomes TagNotExistException or TagAlreadyExistException. A missing snapshot stays a ValueError.

REST catalogs reject both commands. The REST API only has create, get, list, and delete. Rewriting the tag file from the client would leave the server registry pointing at a name whose file is gone, and would skip the permission checks used by the other tag commands.

tag create --time-retained passes the retention through to catalog.create_tag. On replace, omitting --time-retained rewrites the tag as a plain snapshot reference and drops a retention that was already set. That matches the existing tag-file format.

paimon tag rename mydb.users v1 v2
paimon tag replace mydb.users v1 --snapshot-id 3 --time-retained 12h
paimon tag create mydb.users v1 --time-retained 12h

Test plan

• cli_tag_test: rename, name conflict, replace to a snapshot and to latest, create and replace with 12h, missing tag, missing snapshot, replace without --time-retained drops TTL
• rest_tag_test: rename and replace raise NotImplementedError and leave the server tag registry unchanged