`tap run --metadata` is not being treated as metadata during test plan run

When you define metadata from tap run the metadata should be attached to the test plan and accepted by result listeners as metadata. Hence when you attach metadata during tap run you should be able to see in the result viewer.

To reproduce:

• create a test plan
• configure a sqlite result listener
• run `tap run --metadata test=5 test.TapPlan"
• Verify that the value test=5 is saved in the results and can be viewed along with the results from the test steps, for example, the result can be split on test=5 vs test=6.