directive: no support for `formControl`

[SuperITMan]

🚀 Feature request

Current behavior

[ngxFormErrors] directive expects to receive a formControlName. Based on this form control name, it gets the FormControl from the FormGroupDirective (parent ForrmGroup).

The directive cannot receive a FormControl instead of a control name.

Expected behavior

Give the ability to pass a FormControl or a FormControlName depending on the case.

What is the motivation / use case for changing the behavior?

Improving the library.