Select templates: improvments

**Describe the enhancement or change**

Cockpit improvements needed: 
Our linter doesn't like the "any" type.
TypeScript actually reports a typing error for the "isDisabled" property, which seems easily fixed.
Not all our typeahead users specify a "onClearSelection" function, and for those the "X" button was still there but did nothing. I think it is better to not show that button in that case.
