SCIM: Support for PATCH for user updates

**Is your feature request related to a problem? Please describe.**

We have a SCIM Consumer that does not tolerate PUT request for existing users,

**Describe the solution you'd like**
Just as the `SCIMGroupClient` can discern between PUT/PATCH request based on the `ServiceProviderConfig`

The `SCIMUserClient` should be able to achieve the same.

**Describe alternatives you've considered**

We patched the `SCIMUserClient` ourselves to support such PATCH operation

I can volunteer to contribute the support we patched in our instance.