feat(application-settings): implemented allKeys method

[surdu]

PR Checklist

• The PR title follows our guidelines: https://github.com/NativeScript/NativeScript/blob/master/CONTRIBUTING.md#commit-messages.
• There is an issue for the bug/feature this PR is for. To avoid wasting your time, it's best to open a suggestion issue first and wait for approval before working on it.
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• All existing tests are passing: https://github.com/NativeScript/NativeScript/blob/master/DevelopmentWorkflow.md#running-unit-tests.
• Tests for the changes are included - https://github.com/NativeScript/NativeScript/blob/master/WritingUnitTests.md.

What is the current behavior?

There is no way to get all key from application-settings.

What is the new behavior?

There is a method .allKeys() that returns all the keys from application-settings.

Fixes #6210.

[vakrilov]

Hey @surdu - Thanks for the PR!

[vakrilov]

test

[surdu]

@vakrilov Hey! My pleasure 😉

[vakrilov]

test

[radeva]

Hi @surdu ,

Congratulations on being one of the winners in the {N} First-time contributors contest!

You can claim your prize by contacting us at nativescriptwinners[at]progress.com not later than Nov 30th 2018 . Make sure you send us the following info: 
👉Your full name 
👉Your email 
👉Your country or residence 

Best regards,
The NativeScript Team

[surdu]

O, wow! That's awesome! Thank you 😁

[lock]

This thread has been automatically locked since there has not been any recent activity after it was closed. Please open a new issue for related bugs.