GREG-286: Update IGA check for UiB

I removed use of scim-client, which only supported the Sebra-scim at UiB, and instead made use of the abstract IGA client library, which has support for the current RI Scim implementation at UiB.

Note that I did not install the latest version of the abstract IGA client library, since that requires version 2.0.0 of the cerebrum-client, and I did not want to update our dependency on it since I am not familiar with the library.

The IGA client library also support UiB Sebra-scim by the way, and it does this by using scim-client. For interacting with RI Scim it uses the scim2-client library.