Missing support for "Readonly plain text"

[it-management]

There is a missing support for Readonly plain text.
It's possible to put a class form-control-plaintext to the Field manually, but class form-control (or form-select for <select>) persists, which is wrong.

[kosdmit]

I use UneditableField to to avoid unwanted behaviour of 'form-control' class in this case. This Field works well in bundle with 'form-control-plaintext' css_class. For example:

UneditableField('name', css_class='form-control-plaintext', rows=2)

This will produce the following html:

<input type="text" name="name" value="Тестовая компания" maxlength="200" class="uneditable-input form-control-plaintext textinput" rows="2" disabled="disabled" required="" id="id_name">