feat: create user scim v2 endpoint (#9132)

# Which Problems Are Solved
- Adds infrastructure code (basic implementation, error handling,
middlewares, ...) to implement the SCIM v2 interface
- Adds support for the user create SCIM v2 endpoint

# How the Problems Are Solved
- Adds support for the user create SCIM v2 endpoint under `POST
/scim/v2/{orgID}/Users`

# Additional Context

Part of #8140

internal/api/scim/resources/user_mapping.go

@@ -0,0 +1,81 @@
+package resources
+
+import (
+	"context"
+
+	"golang.org/x/text/language"
+
+	"github.com/zitadel/zitadel/internal/command"
+	"github.com/zitadel/zitadel/internal/domain"
+)
+
+func (h *UsersHandler) mapToAddHuman(ctx context.Context, scimUser *ScimUser) (*command.AddHuman, error) {
+	// zitadel has its own state mechanism
+	// ignore scimUser.Active
+	human := &command.AddHuman{
+		Username:    scimUser.UserName,
+		NickName:    scimUser.NickName,
+		DisplayName: scimUser.DisplayName,
+		Email:       h.mapPrimaryEmail(scimUser),
+		Phone:       h.mapPrimaryPhone(scimUser),
+	}
+
+	md, err := h.mapMetadataToCommands(ctx, scimUser)
+	if err != nil {
+		return nil, err
+	}
+	human.Metadata = md
+
+	if scimUser.Password != nil {
+		human.Password = scimUser.Password.String()
+		scimUser.Password = nil
+	}
+
+	if scimUser.Name != nil {
+		human.FirstName = scimUser.Name.GivenName
+		human.LastName = scimUser.Name.FamilyName
+
+		// the direct mapping displayName => displayName has priority
+		// over the formatted name assignment
+		if human.DisplayName == "" {
+			human.DisplayName = scimUser.Name.Formatted
+		}
+	}
+
+	if err := domain.LanguageIsDefined(scimUser.PreferredLanguage); err != nil {
+		human.PreferredLanguage = language.English
+		scimUser.PreferredLanguage = language.English
+	}
+
+	return human, nil
+}
+
+func (h *UsersHandler) mapPrimaryEmail(scimUser *ScimUser) command.Email {
+	for _, email := range scimUser.Emails {
+		if !email.Primary {
+			continue
+		}
+
+		return command.Email{
+			Address:  domain.EmailAddress(email.Value),
+			Verified: h.config.EmailVerified,
+		}
+	}
+
+	return command.Email{}
+}
+
+func (h *UsersHandler) mapPrimaryPhone(scimUser *ScimUser) command.Phone {
+	for _, phone := range scimUser.PhoneNumbers {
+		if !phone.Primary {
+			continue
+		}
+
+		return command.Phone{
+			Number:   domain.PhoneNumber(phone.Value),
+			Verified: h.config.PhoneVerified,
+		}
+	}
+
+	return command.Phone{}
+}