MultiSelect Combo should support clearing input text on selection

[pmiklashevych]

https://www.bryntum.com/forum/viewtopic.php?f=43&t=16841&p=83758#p83758

Add a config to clear text on item selection similar to clearTextOnPickerHide

Try the code below without the listener first. Type in "Ja" and select "Java". See "Java" is selected but "Ja" is in the input.

import Combo from '../../lib/Core/widget/Combo.js';

new Combo({
    listeners : {
        select() {
            if (this.multiSelect) {
                this.input.value = '';
            }
        }
    },
    appendTo    : 'container',
    multiSelect : true,
    style       : 'margin-top:3em',
    label       : 'Skills - multiSelect',
    value       : ['Javascript', 'SQL'],
    items       : [
        'BASIC',
        'COBOL',
        'FORTRAN',
        'DBL',
        'SQL',
        'C/C++',
        'Java',
        'Javascript'
    ],
    width : '100%'
});

[matsbryntse]

Dupe #1335