Functional testing: Test adding an API backend

[bajiat]

Test adding an API backend through the Add API backend form. Report any unexpected issues or errors as Github issues providing steps to reproduce the error. Add the label "bug" to the issues.

[bajiat]

@ashakunt I added the functional testing task for sprint 16 and assigned it to you. Reword this if necessary.

[saralavanip]

Reported the issues below, related to 'Adding API backend' through 'Add API backend form' on Github:
1.https://github.com/apinf/api-umbrella-dashboard/issues/602
2.https://github.com/apinf/api-umbrella-dashboard/issues/603
3.https://github.com/apinf/api-umbrella-dashboard/issues/604
4.https://github.com/apinf/api-umbrella-dashboard/issues/605
5.https://github.com/apinf/api-umbrella-dashboard/issues/599

[bajiat]

@saralavanip @ashakunt Can we close this issue, since it has already been tested?