feat: user grants command side (#1191)

* fix: user grant command side

* fix: user grant command side

* fix: user grant command side check permissions

* fix: unique constraint on user grants

* fix: add usergrant

* fix: add usergrant

* fix: add usergrant

* fix: user grant remove

* Update internal/v2/command/auth_checks.go

Co-authored-by: Livio Amstutz <livio.a@gmail.com>

* Update internal/v2/command/auth_checks.go

Co-authored-by: Livio Amstutz <livio.a@gmail.com>

* Update internal/v2/command/project.go

Co-authored-by: Livio Amstutz <livio.a@gmail.com>

* Update internal/v2/command/user_grant.go

Co-authored-by: Livio Amstutz <livio.a@gmail.com>

* fix: project events

Co-authored-by: Livio Amstutz <livio.a@gmail.com>

internal/v2/domain/user_grant.go

@@ -0,0 +1,26 @@
+package domain
+
+import es_models "github.com/caos/zitadel/internal/eventstore/models"
+
+type UserGrant struct {
+	es_models.ObjectRoot
+
+	State          UserGrantState
+	UserID         string
+	ProjectID      string
+	ProjectGrantID string
+	RoleKeys       []string
+}
+
+type UserGrantState int32
+
+const (
+	UserGrantStateUnspecified UserGrantState = iota
+	UserGrantStateActive
+	UserGrantStateInactive
+	UserGrantStateRemoved
+)
+
+func (u *UserGrant) IsValid() bool {
+	return u.ProjectID != "" && u.UserID != ""
+}