[WIP] SettingToggle Icon Support +Fixes

[duraki]

This is separate issue for tracking _original feature request in #24. There are few PR on this (ie. #38, #37) but both of them has issues due to not implementing nillable horizontalPadding. This issue should track my changes featuring both PR #38 & #37, but with additional options implementing:

• SettingToggle native support for onChange(...) event expecting closure
• SettingToggle native icon support
• Fixes on SettingToggle Icon padding issue (see add action to a SettingToggle control #38 (comment))
  • SettingToggle support for nillable horizontalPadding
  • SettingToggle support for optional edgePadding
• SettingToggle Icon via extension (as expected, ie. what SettingButton currently implements)
• Example usage of SettingToggle with custom Icon

Feature Showcase

[duraki]

Preview provided via:

// SettingExample/PreferencesView.swift

struct PreferencesViews_Previews: PreviewProvider {
    static var previews: some View {
        PreferencesView()
    }
}

[duraki]

Hey @aheze, hope this small contrib helps you a bit. Thanks for open-sourcing and writing this package, really nice to use. I can't request MR for some reason, but the PR #43 implements this feature. I've tried to follow yours/repository codebase expectations as per previous pull requests and your commits.

Cheers 🎉