chore(typedoc): hide some declarations from typedoc document

[Aleksandyr]

Closes #2858

[damyanpetev]

Looking at TypeStrong/typedoc#639 generating just the exported API might not be supported at all, so yeah @hidden it is.
There are more than those though, will update with a full list.

[gedinakova]

None of the Excel, ColumnChooser and TreeGrid related items should be visible.

[damyanpetev]

After latest changes what's left in the API docs are the following not exported items:

import {
    DisplayContainerComponent,
    IgxProcessBarTextTemplateDirective,
    VirtualHelperComponent,
    IValueChangedEventArgs,
} from 'igniteui-angular';