changeColor method
Implementation
void changeColor(Color color) {
final TextMetadata changedMetadata =
(metadata ?? RichTextEditorController.defaultMetadata).copyWith(
color: color,
);
changeStyleOnSelectionChange(
changedMetadata: changedMetadata,
change: TextMetadataChange.fontStyle,
modifiedDeltas: deltas.copy,
selection: selection,
);
}