[Calling][Feature] Custom buttons updatable

[pavelprystinka]

Purpose

• Make Custom buttons updatable after the launch

Does this introduce a breaking change?

• [ ] Yes
• [ ] No

Pull Request Type

What kind of change does this Pull Request introduce?

• [ ] Bugfix
• [x] Feature
• [ ] Code style update (formatting, local variables)
• [ ] Refactoring (no functional changes, no api changes)
• [ ] Documentation content changes
• [ ] Other... Please describe:

Pull request checklist

This PR has considered:

• [ ] Color Theming
• [ ] iOS supported versions (all major versions greater than or equal current target deployment version)
• [ ] VoiceOver and Keyboard Accessibility
• [ ] Internationalization and Right to Left layouts
• [ ] Size classes and window sizes (iPhone vs iPad, notched devices, multitasking, different window sizes, etc)
• [ ] View Data Injection
• [ ] Demo App UI/UX update

How to Test

• Open...
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What to Check

Before	After
Screenshot or description before this change	Screenshot or description with this change

Other Information