Implement test cases for `IXMLDOMElement_removeAttributeNode()` function. Cover the successful removal and failure codes for double removal and `NULL` pointer removal.
The function is currently unimplemented in wine.
This is the recommended first step according to the contribution documentation (do coverage MR first, then implementation MR).
WineTestBot submission can be found here: https://testbot.winehq.org/JobDetails.pl?Key=159792&f101=exe32.report#k1...
The VMs `debian11` and `debian11b` show the following errors, which should be unrelated to this MR.
``` msxml3 domdoc.c:10563: Test failed: got L"xmlns:rdf" domdoc.c:10563: Test failed: got L"xmlns:dcterms" domdoc.c:10563: Test failed: got L"xmlns:foaf" ```
Once this one is merged I'll create the implementation MR.
I tried to match the formatting. If I've missed something please tell me and I'll fix it.