refactor(EditableTextBase, Button) rename PseudoClass update handlers to be more specific

[bundyo]

Rename the PseudoClass update handler names to something more specific
as the TextField method clashes with DateTimePicker plugin method
with the same name, causing its tap handler to be called several times.

PR Checklist

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• Tests for the changes are included - https://github.com/NativeScript/NativeScript/blob/master/WritingUnitTests.md.

What is the new behavior?

No change in behavior, just rename the private methods to be more specific.