Add attributes in the allowed HTML tags in the "Basic HTML" format

[trubach]

We should allow the following attributes to the allowed HTML tags:

1. Add the colspan and rowspan attribute to the <th> element
2. Add the target attribute to the <a> element

illinois_framework_profile/config/install/filter.format.basic_html.yml

Line 20 in 7b25d85

allowed_html: '<em> <strong> <cite> <blockquote cite> <code> <ul type class=""> <ol type start class=""> <li class=""> <dl class=""> <dt class=""> <dd class=""> <h2 id class=""> <h3 id class=""> <h4 id class=""> <h5 id class=""> <h6 id class=""> <p class=""> <br> <img src alt data-entity-type data-entity-uuid data-align data-caption width height class=""> <sup> <sub> <hr> <table role aria-label class=""> <caption> <tbody> <thead> <tfoot class=""> <th id class=""> <td id class=""> <tr id class=""> <q class=""> <address class=""> <div class=""> <span id class=""> <drupal-media alt data-align data-caption data-view-mode data-entity-uuid data-entity-type title> <a href hreflang name data-entity-substitution data-entity-type data-entity-uuid title class=" il-button il-white-blue il-white-orange il-blue il-orange">'