Refactor modal options to expose current/future core options

[edusperoni]

PR Checklist

• The PR title follows our guidelines: https://github.com/NativeScript/NativeScript/blob/master/CONTRIBUTING.md#commit-messages.
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• Tests for the changes are included.

What is the current behavior?

The current exposed options for showModal differs from the options available in the core.

What is the new behavior?

All current and future non-angular options are exposed by leveraging Typescript's Pick type.

#1767 attempts to fix this, but another property has been exposed (android: any), so other PRs would be needed for every new property.

I'm asking for this PR to be considered over #1767

Fixes #1709.

[VladimirAmiorkov]

Hi @edusperoni ,

Thank you for your contribution with this PR and the comments on the #1767 PR. As I see that your PR's code changes have been taken and added to the #1767 PR and as it also contains additional functionality in the form of the new sourceView property of the ModalDialogOptions that is required for some of the ios specific options like the popover to work I suggest we merge that PR and close this one.

[edusperoni]

I don't really care which PR is merged, but that PR is still using the any cast that should be removed and the commits are kind of messy.

[VladimirAmiorkov]

@edusperoni yes I have noticed that, it also is missing a "test" case example. We are going to process it.

[VladimirAmiorkov]

Closing in favor of #1771