Adding duplicate feature should throw message and revert addition in TestScriptor page

[lvanvugt]

When adding a duplicate feature a message should be thrown and the added feature reverted in TestScriptor page.

To Reproduce
Steps to reproduce the behavior execute the following test scenario

No.	Feature	Scenario
0095	Adding Feature	Adding duplicate Feature

in atdd-test-scenarios-and-results.xlsx

Result
The Feature control on the ATDD.TestScriptor page remains while (rightly) no test codeunit has been created (as it already existed).

Expected result
The Feature control on the ATDD.TestScriptor page should be reverted and a message should be shown, telling "Feature already exists. Please update your feature definition so it is unique"

Belonging to #61.

[DavidFeldhoff]

@martonsagi : With 784ed01 I return now that a feature already exists.
That works, so that the feature is not inserted. But let's say I create a second time the feature "First test object". Then I return "That feature already exists.".
So I want to add "First test object 2" instead of "First test object". But then I'm triggered as if it would be a Renaming of the feature which is not true as it wasn't inserted in the first place. Could you have a look at it?

[martonsagi]

@DavidFeldhoff What is in the message object that you send back to the UI in this case?

[DavidFeldhoff]

I made a change here, so that I now return false in the procedure correctly and the "userCancelledSaving" variable is true. But the issue of my previous comment remains.
b3d67b3#diff-0fc540fe39809847cade5bbff4841e10f7963991d25714e61c7cb5d458736f31R220
https://github.com/fluxxus-nl/ATDD.TestScriptor.VSCodeExtension/blob/master/web-ui/src/app.ts#L45

[lvanvugt]

This is clearly no finished

[DavidFeldhoff]

@martonsagi I'll put it on your name only as I return the correct state (in my eyes). If I'm missing something or if I can help you, let's have a chat.

[martonsagi]

#125 has been implemented by clearing the value after failure.
The renaming popup showed earlier becuase the list values are simple text values, there is no state property handling from where we would know that a certain value was invalidated previously. That would need a redesign of the feature pane.

[lvanvugt]

Agree with closing this issue because of fix for #125.