Parse data tag from message type of testresult.xml

In the current version of test results parsing - data tag from messages are ignored.
Only data tags from incidents are parsed.

results.go:
// IncidentHeader provides the fields that are common for Incident
// and Message, basically the file name and line numbers of
// where the message was produced or the incident happened.

type IncidentHeader struct

{ Type string `xml:"type,attr"` File string `xml:"file,attr"` Line int `xml:"line,attr"` }

type Message struct

{ IncidentHeader Description string }

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Example of ignored data tag:

example
project: qt qsvg
tst_QSvgDevice:

void tst_QSvgDevice::play_data()

{ QTest::addColumn<QString>("tag name"); // we only use the tag name QTest::newRow( "lines" ); QTest::newRow( "font" ); QTest::newRow( "polyline" ); }

void tst_QSvgDevice::play()

{ QSKIP("This test needs some redoing, this is just a temp measure until I work it out"); }

generated xml result file:

<TestFunction name="play">
<Message type="skip" file="tst_qsvgdevice.cpp" line="364">
<DataTag><![CDATA[lines]]></DataTag>
<Description><![CDATA[This test needs some redoing, this is just a temp measure until I work it out]]></Description>
</Message>
<Message type="skip" file="tst_qsvgdevice.cpp" line="364">
<DataTag><![CDATA[font]]></DataTag>
<Description><![CDATA[This test needs some redoing, this is just a temp measure until I work it out]]></Description>
</Message>