feat(api): accept user and team locators on grants

.changeset/grant-api-locators.md

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+---
+"@zitadel/server": minor
+---
+
+Callers can create grants by user identifier or team name, not only by id. Create, get, and list name the bound person as `user` (`user_id`) or `team` (`team_id`) and drop `principal_type` / `principal_id`. `expand: ["principal"]` adds extra fields on that same object. Creating by identifier always returns 201 except self-grant; it does not reveal whether the address matched.