chore: move converter methods users v2 to separate converter package + add tests (#10567)

# Which Problems Are Solved

As requested by @adlerhurst in
https://github.com/zitadel/zitadel/pull/10415#discussion_r2298087711 , I
am moving the refactoring of v2 user converter methods to a separate PR

# How the Problems Are Solved

Cherry-pick 648c234caf

# Additional Context

Parent of https://github.com/zitadel/zitadel/pull/10415

(cherry picked from commit b604615cab)

internal/api/grpc/user/v2/convert/human.go

@@ -0,0 +1,61 @@
+package convert
+
+import (
+	"github.com/muhlemmer/gu"
+	"google.golang.org/protobuf/types/known/timestamppb"
+
+	"github.com/zitadel/zitadel/internal/domain"
+	"github.com/zitadel/zitadel/internal/query"
+	"github.com/zitadel/zitadel/pkg/grpc/user/v2"
+)
+
+func humanToPb(userQ *query.Human, assetPrefix, owner string) *user.HumanUser {
+	if userQ == nil {
+		return nil
+	}
+
+	var passwordChanged, mfaInitSkipped *timestamppb.Timestamp
+	if !userQ.PasswordChanged.IsZero() {
+		passwordChanged = timestamppb.New(userQ.PasswordChanged)
+	}
+	if !userQ.MFAInitSkipped.IsZero() {
+		mfaInitSkipped = timestamppb.New(userQ.MFAInitSkipped)
+	}
+	return &user.HumanUser{
+		Profile: &user.HumanProfile{
+			GivenName:         userQ.FirstName,
+			FamilyName:        userQ.LastName,
+			NickName:          gu.Ptr(userQ.NickName),
+			DisplayName:       gu.Ptr(userQ.DisplayName),
+			PreferredLanguage: gu.Ptr(userQ.PreferredLanguage.String()),
+			Gender:            gu.Ptr(genderToPb(userQ.Gender)),
+			AvatarUrl:         domain.AvatarURL(assetPrefix, owner, userQ.AvatarKey),
+		},
+		Email: &user.HumanEmail{
+			Email:      string(userQ.Email),
+			IsVerified: userQ.IsEmailVerified,
+		},
+		Phone: &user.HumanPhone{
+			Phone:      string(userQ.Phone),
+			IsVerified: userQ.IsPhoneVerified,
+		},
+		PasswordChangeRequired: userQ.PasswordChangeRequired,
+		PasswordChanged:        passwordChanged,
+		MfaInitSkipped:         mfaInitSkipped,
+	}
+}
+
+func genderToPb(gender domain.Gender) user.Gender {
+	switch gender {
+	case domain.GenderDiverse:
+		return user.Gender_GENDER_DIVERSE
+	case domain.GenderFemale:
+		return user.Gender_GENDER_FEMALE
+	case domain.GenderMale:
+		return user.Gender_GENDER_MALE
+	case domain.GenderUnspecified:
+		return user.Gender_GENDER_UNSPECIFIED
+	default:
+		return user.Gender_GENDER_UNSPECIFIED
+	}
+}