`teams update` should accept `-f <file>` and deprecate the display-only flags

[mmanciop]

Problem

dash0 teams update only supports imperative flags (--name, --color-from, --color-to) and can only change a team's display settings.

teams create already accepts a declarative TeamDefinitionV1Alpha1 document via -f <file>, and every other asset type's update subcommand (dashboards update, views update, check-rules update, etc.) is file-based.
teams update is the odd one out: it can't take the same document shape teams create/teams get -o yaml produce, and it can't touch anything outside of display (e.g. spec.members) — that has to go through the separate add-members/remove-members commands.

This breaks the export → edit → reapply workflow that works for every other asset type: a team YAML pulled from teams get -o yaml can't be fed back into teams update.

Proposed behavior

• teams update <id> -f <file> accepts a TeamDefinitionV1Alpha1 document (same shape as teams create -f) and updates the team accordingly.
• The existing --name, --color-from, --color-to flags continue to work but are deprecated in favor of -f.
• Using the deprecated flags does not break existing scripts (backward compatible).