Fix nuxeo-search-form not providing accessible information

Related to WCAG 2.1 level A criteria 1.3.1:
https://www.w3.org/WAI/WCAG21/quickref/#info-and-relationships

See spreadsheet linked in WEBUI-193 for all references

Form elements must have labels

Recommendation to fix

Fix any of the following:
aria-label attribute does not exist or is empty
aria-labelledby attribute does not exist, references elements that do not exist or references elements that are empty
Form element does not have an implicit (wrapped) <label>
Form element does not have an explicit <label>
Element has no title attribute
Element has an empty placeholder attribute
Element's default semantics were not overridden with role="none" or role="presentation"