SearchApiBlockForm missing title

Problem/Motivation

When using the SearchApiBlockform from wxt_library the search block form is missing the label attribute. The markup looks like this:

<div class="form-item js-form-item form-type-search js-form-type-search form-item-search-api-fulltext js-form-item-search-api-fulltext form-no-label form-group">
<input data-drupal-selector="wb-srch-q" class="form-search form-control" placeholder="Search website" type="search" id="wb-srch-q" name="search_api_fulltext" value="" size="27" maxlength="128">
</div>

Instead of:

<div class="form-item js-form-item form-type-search js-form-type-search form-item-search-api-fulltext js-form-item-search-api-fulltext form-no-label form-group">
<label for="wb-srch-q" class="control-label sr-only">Search</label>
<input data-drupal-selector="wb-srch-q" class="form-search form-control" placeholder="Search website" type="search" id="wb-srch-q" name="search_api_fulltext" value="" size="27" maxlength="128">
</div>

Steps to reproduce

Just install wxt and add the SearchApiBlock.

Proposed resolution

Add the label exactly as is done in SearchBlockForm.php in wxt_library.

Remaining tasks

User interface changes

None.

API changes

None.

Data model changes

None.