[A11Y] Improve accessibility for discussion reply count on post stream (#3090)

* Add class to remove all UA styles from a button

* Improve classList utilisation

* Simplify JSX

* Use classlist instead of concatenation

* Fix reply count focusable when not acting as a button

* Add SR only class

* Add new reply count translations

* Use cleaner translations

* Remove unused import

* Add missing new line

* Delete Accessibility.less

* Use existing `.visually-hidden` class

* Format

* Fix locale formatting

framework/core/less/common/Button.less

@@ -231,3 +231,36 @@
   font-weight: bold;
   margin-left: 10px;
 }
+
+// Remove all user-agent styles from the Button
+.Button--ua-reset {
+  border: none;
+  margin: 0;
+  padding: 0;
+  width: auto;
+  overflow: visible;
+  text-align: inherit;
+  vertical-align: inherit;
+
+  background: transparent;
+
+  /* inherit font & color from ancestor */
+  color: inherit;
+  font: inherit;
+
+  /* Normalize `line-height`. Cannot be changed from `normal` in Firefox 4+. */
+  line-height: normal;
+
+  /* Corrects font smoothing for webkit */
+  -webkit-font-smoothing: inherit;
+  -moz-osx-font-smoothing: inherit;
+
+  /* Corrects inability to style clickable `input` types in iOS */
+  -webkit-appearance: none;
+  appearance: none;
+
+  &::-moz-focus-inner {
+    border: 0;
+    padding: 0;
+  }
+}