[Microsuite] Fix and Re-enable failing Text Microsuite Test

[arpitmathur]

There is 1 test failure in the Text Microsuite tests Port. This test has been disabled as part of the port.

Test details: SubArea="Font\RelativeFontUriTest" Name="RelativeFontUriTest"

This test is throwing an System.InvalidOperationException when it fails.

System.InvalidOperationException: The 'ResourceAssembly' property of the 'Application' type cannot be changed after it has been set.