Set the default width of the MultiColumnComboBox columns based on the input width.

In order to position the Popup of the MultiColumnComboBox correctly, we need each column to have fixed width.

Currently, we are setting the default width to 200px for each column that has not width set from the options.

We can add a second option to take the width of the input, subtract the width of the columns with fixed width and divide the remaining space between the other columns.