Add functest healthcheck test suite

Add functest healthcheck test suite

- Add Functest healthcheck tier to Dovetail as new test suite
- Intention is that these test cases are not part of mandatory
test cases in compliance program
- Use for debug and SUT pre-flight check
- May consider running tc001 (connection_check) at other
test execution stages to determine if SUT is still functioning, as
this test takes < 10 sec (more important as test complexity increases
such as in vnf test tier)
- Replacement for patch:

https://gerrit.opnfv.org/gerrit/#/c/52461/

- Removed CI filters, as suggested

Change-Id: I2e72931b27e43359d6250f6959a17af8526c5094
Signed-off-by: Eddie Arrage <eddie.arrage@huawei.com>