Remove global button styling (#9607)

Move remaining button and link related styles from _global to _nativebutton and _link.

themes/src/main/themes/VAADIN/themes/valo/components/_link.scss

@@ -30,6 +30,7 @@ $v-link-cursor: pointer !default;
     @include valo-link-style;
 
     a {
+      @include valo-link-style;
       cursor: inherit;
       color: inherit;
       text-decoration: inherit;

themes/src/main/themes/VAADIN/themes/valo/components/_nativebutton.scss

@@ -6,6 +6,13 @@
  * @group nativebutton
  */
 @mixin valo-nativebutton ($primary-stylename: v-nativebutton) {
+
+  button {
+    font: inherit;
+    font-weight: 400;
+    line-height: $v-line-height;
+  }
+
   .#{$primary-stylename} {
     -webkit-touch-callout: none;
   }

themes/src/main/themes/VAADIN/themes/valo/shared/_global.scss

@@ -329,16 +329,6 @@ $valo-shared-pathPrefix: null;
     @include valo-nativeselect-select-style;
   }
 
-  button {
-    font: inherit;
-    font-weight: 400;
-    line-height: $v-line-height;
-  }
-
-  a {
-    @include valo-link-style;
-  }
-
   .v-disabled {
     cursor: default !important;
   }