Update global link hover color from orange to blue (--Blue-400) (#13344)

* base-styles.scss: update a:hover to --Blue-400
- deprecates #df6b0e

* preserve a.warning:hover orange color w/ #ceafa22

* Revert "preserve a.warning:hover orange color w/ #ceafa22"

This reverts commit d0efb923808bbc43e7f955fd8ce3e95f6a124c1f.

* create-account: rm .warning style from help link
- supports #ceafa2

ui/css/base-styles.scss

@@ -45,7 +45,6 @@ html {
 
 /*
   This warning class is used in the following files still:
-  /ui/pages/create-account/import-account/json.js
   /ui/pages/confirm-add-suggested-token/confirm-add-suggested-token.component.js
 */
 .warning {
@@ -72,7 +71,7 @@ a {
 }
 
 a:hover {
-  color: #df6b0e;
+  color: var(--Blue-400);
 }
 
 input.large-input,

ui/pages/create-account/import-account/index.scss

@@ -56,6 +56,10 @@
     margin-top: 34px;
   }
 
+  &__help-link {
+    color: var(--primary-blue);
+  }
+
   &__input-password {
     @include Paragraph;
 

ui/pages/create-account/import-account/json.js

@@ -28,7 +28,7 @@ class JsonImportSubview extends Component {
       <div className="new-account-import-form__json">
         <p>{this.context.t('usedByClients')}</p>
         <a
-          className="warning"
+          className="new-account-import-form__help-link"
           href={HELP_LINK}
           target="_blank"
           rel="noopener noreferrer"