Add outlines to issue right sidebar links

Some of the links and buttons in the issue right sidebar do not show
an outline when tabbing to them. This is poor accessibility which this
commit fixes.

app/assets/javascripts/sidebar/components/lock/lock_issue_sidebar.vue

@@ -108,7 +108,7 @@ export default {
       {{ sprintf(__('Lock %{issuableDisplayName}'), { issuableDisplayName: issuableDisplayName }) }}
       <button
         v-if="isEditable"
-        class="float-right lock-edit"
+        class="float-right lock-edit btn-link"
         type="button"
         data-track-event="click_edit_button"
         data-track-label="right_sidebar"

app/assets/javascripts/sidebar/components/participants/participants.vue

@@ -127,7 +127,7 @@ export default {
     <div v-if="hasMoreParticipants" class="participants-more hide-collapsed">
       <button
         type="button"
-        class="btn-transparent btn-blank js-toggle-participants-button"
+        class="btn-transparent btn-link js-toggle-participants-button"
         @click="toggleMoreParticipants"
       >
         {{ toggleLabel }}

app/assets/stylesheets/framework/buttons.scss

@@ -447,6 +447,7 @@
   font-weight: normal;
   border-radius: 0;
   border-color: transparent;
+  border-width: 0;
 
   &:hover,
   &:active,

app/assets/stylesheets/pages/issuable.scss

@@ -187,7 +187,6 @@
 
   .btn-link {
     color: inherit;
-    outline: none;
   }
 
   .issuable-header-text {
@@ -260,17 +259,6 @@
     a.edit-link:not([href]):hover {
       color: rgba($gray-normal, 0.2);
     }
-
-    .lock-edit, // uses same style, different js behaviour
-    .edit-link {
-      @extend .btn-blank;
-      color: $gl-text-color;
-
-      &:hover {
-        text-decoration: underline;
-        color: $blue-800;
-      }
-    }
   }
 
   .cross-project-reference {
@@ -689,7 +677,6 @@
   }
 
   .btn-link {
-    outline: none;
     padding: 0;
   }
 

ee/app/assets/javascripts/vue_shared/components/sidebar/epics_select/dropdown_title.vue

@@ -32,7 +32,7 @@ export default {
     </div>
     <template v-if="canEdit">
       <gl-link
-        class="btn btn-blank float-right sidebar-dropdown-toggle"
+        class="edit-link float-right sidebar-dropdown-toggle"
         @click="$emit('onClickEdit', $event)"
         >{{ __('Edit') }}</gl-link
       >