Allow collecting data from EUNE, NA, KR on top of EUW

- match_collector: query API and build collections for each platform
- match_collector: aggregate champion stats of each platform in one collection with platform annotations
- frontend: replace stats to count matches in platform-specific collections
- frontend: replace "EUW Challengers" with all supported platforms
- dev: adapted scripts to count match in platforms

frontend/components/nav/SideBar.vue

@@ -137,7 +137,10 @@ if (route.path.startsWith('/tierlist/')) {
         <h3 style="font-size: 18px; font-weight: 200; opacity: 0.5">Loading stats...</h3>
       </template>
       <h3 style="font-size: 18px; font-weight: 200; margin-top: 10px; margin-bottom: 10px">
-        EUW Challenger only
+        Challenger only
+      </h3>
+      <h3 style="font-size: 18px; font-weight: 200; margin-top: 10px; margin-bottom: 10px">
+        EUW/EUNE/NA/KR
       </h3>
       <NuxtLink to="/about"><h3>About</h3></NuxtLink>
       <h2 style="font-size: 10px; font-weight: 200; margin-top: 3px; margin-right: 10px">