Convert comment label buttons from <a> to <button>

The post buttons (Reply, Delete, etc.) were converted to <button> quite
a while ago, and these ones should be switched over for the same reasons
as those were (accessibility, more semantic), as well as being able to
support the error messages from Intercooler.

tildes/scss/modules/_btn.scss

@@ -58,18 +58,17 @@
   margin: 0 0.4rem;
   padding: 0.2rem;
 
+  background: none;
+  border: 0;
+
   font-size: 0.6rem;
   font-weight: bold;
   text-transform: capitalize;
 
   cursor: pointer;
 
-  &.btn {
-    height: 1rem;
-    text-transform: capitalize;
-  }
-
   &.btn-used {
+    height: 1rem;
     border: 1px solid;
   }
 }

tildes/scss/modules/_comment.scss

@@ -133,10 +133,16 @@
   margin: 0;
   padding: 0 1rem;
   justify-content: space-between;
+  align-items: center;
 
   @media (min-width: $size-md) {
     justify-content: left;
   }
+
+  // Wrap error message onto a new line
+  .text-status-message {
+    min-width: 100%;
+  }
 }
 
 .comment-label-count {

tildes/static/js/behaviors/comment-label-button.js

@@ -24,7 +24,7 @@ $.onmount("[data-js-comment-label-button]", function() {
 
         var labeltemplate = document.querySelector("#comment-label-options");
         var clone = document.importNode(labeltemplate.content, true);
-        var options = clone.querySelectorAll("a");
+        var options = clone.querySelectorAll("button");
 
         for (var i = 0; i < options.length; i++) {
             var label = options[i];

tildes/tildes/templates/macros/comments.jinja2

@@ -246,12 +246,12 @@
     <menu class="comment-label-buttons">
       {% for label in options if request.user.is_label_available(label) %}
         <li>
-          <a class="btn-comment-label btn-comment-label-{{ label.name|lower }}"
+          <button class="btn-comment-label btn-comment-label-{{ label.name|lower }}"
             data-js-label-name="{{ label.name|lower }}"
             {% if label.reason_prompt %}
               data-js-reason-prompt="{{ label.reason_prompt }}"
             {% endif %}
-          >{{ label.name|lower }}{% if label.reason_prompt %}...{% endif %}</a>
+          >{{ label.name|lower }}{% if label.reason_prompt %}...{% endif %}</button>
         </li>
       {% endfor %}
     </menu>