Added logout step for acceptance tests

[PVince81]

Description

Added logout step.
Added logout test case that includes the step and checks that the login
page appears after logging out.

Related Issue

Motivation and Context

Needed to be able to log out in some test cases, especially the public link ones.

How Has This Been Tested?

• manual run

Screenshots (if appropriate):

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• Technical debt
• Tests

Checklist:

• Code changes
• Unit tests added
• Acceptance tests added
• Documentation ticket raised:

[PVince81]

@individual-it I need help here: for some reason it does not click on the menu button. In VNC I see that the menu did not open.

Still, I see many other test cases that use the same approach for the menu using the phoenixPage.navigateToUsingMenu() method from which I borrowed the approach.

I don't get why the menu doesn't open in my case. Am I using the page object in the wrong place ?

[PVince81]

This PR is required to be able to properly write public link tests for #1951

[ownclouders]

💥 Acceptance tests webUILogin failed. Please find the screenshots inside ...

https://drone.owncloud.com/owncloud/phoenix/5314/

[PVince81]

solved: I forgot to return the promise

[ownclouders]

💥 Acceptance tests webUITrashbin failed. Please find the screenshots inside ...

https://drone.owncloud.com/owncloud/phoenix/5336/

[individual-it]

the logout test itself is good, for the the public link test I would suggest to make the creation of the public link a Given step that is executed using the API and then there is no problem with the logout

[PVince81]

@individual-it oops, I didn't intend to checkin the public link test here. I'll remove.

[PVince81]

@individual-it removed share test, please approve

[ownclouders]

💥 Acceptance tests webUITrashbin failed. Please find the screenshots inside ...

https://drone.owncloud.com/owncloud/phoenix/5347/