Load Samples app Pages within Frame

[MartinZikmund]

GitHub Issue (If applicable): closes #4684

PR Type

What kind of change does this PR introduce?

• Feature

What is the current behavior?

SamplesApp Page samples are instantiated using Activator.

What is the new behavior?

Page samples are navigated to using a Frame. This ensures their Page.Frame property is not null and OnNavigatedTo method is called.

PR Checklist

Please check if your PR fulfills the following requirements:

• [ ] Docs have been added/updated which fit documentation template (for bug fixes / features)
• [ ] Unit Tests and/or UI Tests for the changes have been added (for bug fixes / features) (if applicable)
• [ ] Validated PR Screenshots Compare Test Run results.
• [x] Contains NO breaking changes
• [x] Associated with an issue (GitHub or internal) and uses the automatic close keywords.
• [x] Commits must be following the Conventional Commits specification.

[gitpod-io[bot]]

[MartinZikmund]

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[jeromelaban]

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[agneszitte]

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