Fix invalid behavior of MoveToAttribute methods

[Maximys]

This PR fix Issue-34443.

[krwq]

do _curDepth or _bInReadBinary need any adjustments? (I've done quick tests with checking XmlReader.Depth and that looks consistent across readers so possibly the answer is no)

[krwq]

@Maximys I gave this a second look and per https://docs.microsoft.com/en-us/dotnet/api/system.xml.xmlreader.movetoattribute?view=net-6.0#System_Xml_XmlReader_MoveToAttribute_System_String_ the single string MoveToAttribute can take a qualified name while (localName, ns) does not. I.e. see implementation https://github.com/dotnet/runtime/blob/main/src/libraries/System.Private.Xml/src/System/Xml/Core/XmlTextReaderImpl.cs#L1043 here - can you add tests to ensure this scenario works? (I'm not sure if it worked without this change as well so might be worth validating that as well)

[krwq]

@Maximys have you perhaps had a chance to test out what I suggested above?

[Maximys]

@krwq , am I correctly understand you, that your want to check is next XML will read fine or not:
"<root><child someNamespace:attr1='value1'><other /></child></root>"

[danmoseley]

@krwq question for you above

[krwq]

@Maximys sorry for late response, I want you to exercise if XmlNodeReader.MoveToAttribute(string) will work correctly if you specify fully qualified name of the attribute (i.e. someNamespace:attr1 from your example but assuming that namespace is defined somewhere). If it doesn't work verify if it was also the case before your change.

[krwq]

@Maximys had a chance to look in the scenario I mentioned above?

[danmoseley]

I'm going to close this due to not hearing back. Feel free to reopen if you wish to continue.