Pm binding conversion error

[dnenov]

Purpose

A small PR addressing binding issues with the Numerical Up/Down custom user control.

This PR cherry-picks and updates some of the changes from #14506. The old one will be closed in favor of multiple smaller PRs.

Declarations

Check these if you believe they are true

• The codebase is in a better state after this PR
• Is documented according to the standards
• The level of testing this PR includes is appropriate
• User facing strings, if any, are extracted into *.resx files
• All tests pass using the self-service CI.
• Snapshot of UI changes, if any.
• Changes to the API follow Semantic Versioning and are documented in the API Changes document.
• This PR modifies some build requirements and the readme is updated
• This PR contains no files larger than 50 MB

Release Notes

• previously the dependency property of the numeric control was an integer, which would work, but would be raising a conversion error in the background

Reviewers

@reddyashish
@mjkkirschner

FYIs

@Amoursol