Fix text color usage for different visual states when using a button with character spacing

[kenkosmowski]

This PR fixes an issue where title color of a button on iOS won't update when switching between different visual states and using character spacing.

Description of Change

I only added a call to UpdateText() on ButtonLayoutRenderer when TextColor property changed.

API Changes

None

Platforms Affected

• iOS

Behavioral/Visual Changes

Title color of button gets updated when visual state changed,

Before/After Screenshots

Not applicable

Testing Procedure

Use a button with character spacing and add different text colors for different visual states. Switching between these visual states will change the text color.

PR Checklist

• Targets the correct branch
• Tests are passing (or failures are unrelated)

[jfversluis]

/azp run

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[azure-pipelines]

Azure Pipelines successfully started running 1 pipeline(s).

[thisisthekap]

@jfversluis Any chance that this one is making it into a Xamarin.Forms service release?

[jfversluis]

Now that we're so close to the sunsetting of Xamarin.Forms unfortunately we won't be able to take this in anymore, we're really sorry about that. Nevertheless, thank you so much for your time and effort that you have put into this PR.

Please have a look at the evolution of Xamarin.Forms, .NET MAUI. A lot of development has been going on there. Hopefully this issue was already fixed in that codebase. If not, feel free to port this over to there.

Again, thank you so much for being a contributor and Xamarin.Forms user!