Improve readability of badges and pills (#12360)

* Improve readability of badges and pills

Badges will now always use light theme colors so that they become white-on-gray in both themes, and the contrast of pills has been increased so that they use primary action colors as the background.

* Fix tests

res/css/views/elements/_Pill.pcss

@@ -42,6 +42,10 @@ limitations under the License.
         background-color: $pill-hover-bg-color !important; /* To override .markdown-body */
     }
 
+    &:active {
+        background-color: $pill-press-bg-color !important; /* To override .markdown-body */
+    }
+
     &.mx_UserPill_me:hover {
         background-color: var(
             --cpd-color-bg-critical-hovered