RadDataForm Picker Validation Issue

[CatchABus]

Tell us about the problem

In the case of RadDataForm 'Picker' entities when their options consist of keys and labels, their validators are trying to validate label instead of value. This has been tested with manual validation. Is this behaviour correct?

EDITED: Same goes for manual commit. Label is commited as value instead of key.

Which platform(s) does your issue occur on?

Platform: Android

Please provide the following version numbers that your issue occurs with:

• Progress NativeScript UI plugin version: nativescript-ui-dataform ^6.0.0
• CLI: 6.4.1
• Cross-platform modules: 6.5.0
• Runtime: 6.4.1

Please tell us how to recreate the issue in as much detail as possible.

In the case of RadDataForm 'Picker' entities when their options consist of keys and labels, their validators are trying to validate label instead of value. This has been tested with manual validation. Just try validating and commiting a form that includes a 'Picker' field consisted of keys and values using 'valuesProvider', with form manual validation and commit.

[NickIliev]

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## Please, provide the details below:

### Tell us about the problem
_Please, ensure your title is less than 63 characters long and starts with a capital
letter._

### Which platform(s) does your issue occur on?
_iOS/Android/Both (if applicable tell us the specific version of the platform)_

### Please provide the following version numbers that your issue occurs with:
- **Progress NativeScript UI plugin version:** (the version of nativescript-ui-* in the `package.json`)
- **CLI:** (run `tns --version` to fetch it)
- **Cross-platform modules:** (the version of tns-core-modules in the `package.json`)
- **Runtime(s):** (the `"tns-android"` and `"tns-ios"` properties in the `package.json`)

### Please tell us how to recreate the issue in as much detail as possible.
1. Start the application ..
2. ...

### Is there code involved? If so, please share the minimal amount of code needed to recreate the problem.
_(You can paste entire code snippets, link to playground demo or attach a runnable project)_

[CatchABus]

@NickIliev Done!