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/string.go

@@ -0,0 +1,28 @@
+package schemas
+
+import "encoding/json"
+
+// WriteOnlyString a write only string is not serializable to json.
+// in the SCIM RFC it has a mutability of writeOnly.
+// This increases security to really ensure this is never sent to a client.
+type WriteOnlyString string
+
+func NewWriteOnlyString(s string) *WriteOnlyString {
+	wos := WriteOnlyString(s)
+	return &wos
+}
+
+func (s *WriteOnlyString) MarshalJSON() ([]byte, error) {
+	return []byte("null"), nil
+}
+
+func (s *WriteOnlyString) UnmarshalJSON(bytes []byte) error {
+	var str string
+	err := json.Unmarshal(bytes, &str)
+	*s = WriteOnlyString(str)
+	return err
+}
+
+func (s *WriteOnlyString) String() string {
+	return string(*s)
+}