Fix defect when other plugins add a GrailsSpecTestType.

The plugin previously decided whether it needed to add a spock
functional test type by seeing if functionalTests contained
any instances of GrailsSpecTestType.  This can cause a
functional spock type to not be added when other plugins,
e.g. selenium, also add a GrailsSpecTestType.

By changing the check to also consider the name and
relativeSourcePath, the spock type gets added for
functional tests, even when selenium is also present.