Text input is opened in HTML if an additional answer is added

[DmytroAlipov]

Steps to Reproduce:

1. Go to Studio
2. In unit
3. Add new component Problem "Text input"
4. Fill in at least question and answers
5. Add one more answer
6. Save
7. Open problem on edit

It is expected to be opened as standard Text input but opens as markup editing.

---

This issue appears for a specific scenario:
Suppose an incorrect answer option is added to a text problem. In this case, the markup contains the tag.

Then the markup looks something like this:

<problem>
    <stringresponse answer="correct" type="ci">
        <div>some question</div>
        <correcthint>
            <div>some text</div>
        </correcthint>
        <stringequalhint answer="incorrect"></stringequalhint>
        <additional_answer answer="correct"></additional_answer>
        <textline size="20"></textline>
    </stringresponse>
</problem>

If there is an incorrect answer, feedback must be present for the first correct answer. In this case, when you reopen the issue, it will appear in standard view rather than as markup.