[Feature request] Add support for NUnit test properties

[elv1s42]

When using NUnit, we can create custom properties for different purposes:

[Test]
[Description("This test tests awesome features")]
[Property("Priority", "High")]
[Property("Severity", "High")]
[Property("Subsystem", "User dashboard")]
public async Task TestDashboardLogin()
{
  // test
}

These properties are saved in the NUnit .xml result file:

<test-case id="0-2815" name="TestDashboardLogin" fullname="Tests.Dashboard.TestDashboardLogin" methodname="TestDashboardLogin" classname="Tests.Dashboard" runstate="Runnable" seed="949643898" result="Passed" start-time="2023-10-24T12:09:06.3087925Z" end-time="2023-10-24T12:09:12.0604303Z" duration="5.751055" asserts="0">
  <properties>
    <property name="Description" value="This test tests awesome features"/>
    <property name="Priority" value="High"/>
    <property name="Severity" value="High"/>
    <property name="Subsystem" value="User dashboard"/>
  </properties>
  <output>
  </output>
  <attachments>
  </attachments>
</test-case>

I think it will make sense to include these properties as test metadata to have them in TeamCity. They will be visible in TeamCity UI, and they will be accessible via TeamCity API:

<metadata count="15">
  <typedValues name="Description" type="text" value="This test tests awesome features"/>
  <typedValues name="Priority" type="text" value="High"/>
  <typedValues name="Severity" type="text" value="High"/>
  <typedValues name="Subsystem" type="text" value="User dashboard"/>
</metadata>