[MultiSelect] itemDisabled is not invoked for custom items

[ipeshev]

Describe the bug

1. itemDisabled callback is not invoked for custom added items ( not present in [data] list )
2. when filter does not find anything disabled item is enabled

To Reproduce

1. https://codesandbox.io/s/billowing-platform-h4ihdv?file=/src/app/app.component.ts
2. https://codesandbox.io/s/gallant-breeze-ywfb4n?file=/src/app/app.component.ts

Expected behavior

1. itemDisabled callback should be invoked for custom added items.
2. disabled items should not get enabled

Broken in

v7.0.2