Support multiple test attributes

[KhaledMohamedP]

This PR addresses this issue here #16

Support multiple test attributes

{
  "rules": {
    "test-selectors/button": [
      "warn",
      "always",
      { "htmlOnly": true, "testAttribute": ["data-testid", "testId"] }
    ]
}

[anichols-ht]

This seems reasonable to me, but I'll wait for @davidcalhoun to give the final go.

[davidcalhoun]

Great, thank you for the PR! Looks ok on first glance, I haven't had a chance to test it out yet.