Fix publish failures when using embedded db credentials

[fujihara]

Summary

• Publishing a workbook with --db-username/--db-password/--save-db-password or --oauth-username always failed with ValueError: Connection must have a server address, because the ConnectionItem built for the workbook's connections= payload never set server_address. tableauserverclient 0.41 now hard-requires it.
• Fixing that surfaced a second latent bug: publish_workbook_file() passed the bare ConnectionItem instead of wrapping it in a list, causing TypeError: object of type 'ConnectionItem' has no len().
• Added a new optional --db-server CLI flag so users can supply the database server address to associate with the embedded connection credentials. When omitted, server_address is left unset (None), matching the flag's optional nature.
• Fixed publish_workbook_file() to pass connections=[credentials] (a list) instead of the bare ConnectionItem, matching what tableauserverclient expects.
• Added localized help text for the new flag (publish.options.db-server) across all supported locales (de, en, es, fr, ga, it, ja, ko, pt, sv, zh), including recompiled .mo catalogs.

Test plan

• python -m pytest tests/ -v — 318 passed, 2 skipped (pre-existing, unrelated), 0 failed
• python -m pytest tests/commands/test_publish_command.py -v — 10/10 passing, including coverage for server_address being set from --db-server and for the None case, and for the wrapped-list connections payload
• Verified tabcmd publish --help renders the new --db-server flag and localized help text (spot-checked en and de/pt via LANG override)
• Manually reproduced the original failure and confirmed the patched flow builds a valid publish request (mocked server.workbooks.publish call)