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/schemas/schemas.go

@@ -0,0 +1,20 @@
+package schemas
+
+type ScimSchemaType string
+type ScimResourceTypeSingular string
+type ScimResourceTypePlural string
+
+const (
+	idPrefixMessages        = "urn:ietf:params:scim:api:messages:2.0:"
+	idPrefixCore            = "urn:ietf:params:scim:schemas:core:2.0:"
+	idPrefixZitadelMessages = "urn:ietf:params:scim:api:zitadel:messages:2.0:"
+
+	IdUser               ScimSchemaType = idPrefixCore + "User"
+	IdError              ScimSchemaType = idPrefixMessages + "Error"
+	IdZitadelErrorDetail ScimSchemaType = idPrefixZitadelMessages + "ErrorDetail"
+
+	UserResourceType  ScimResourceTypeSingular = "User"
+	UsersResourceType ScimResourceTypePlural   = "Users"
+
+	HandlerPrefix = "/scim/v2"
+)