Move SPI repo tests into the main narayana repo

The Narayana SPI repo contains some tests which test that the Narayana implementation of the SPI passes. The SPI should not be tied to an implementation, in particular this creates a circular dependency.

Any third party that implements any parts of the SPI should add their own testing and we don't provide a TCK at this time.

Narayana already does some SPI testing in one of its maven modules (org.jboss.narayana.jta:narayana-spi) so that would be a good place for relocating the tests.