feat(tags): add minimum vote count for top tags & provide official tags

Add configuration: `BEATMAP_TAG_TOP_COUNT` to control the minimun vote count

Tips: this is 10 in osu-web, but private server doesn't have enough player so we use 2 as default value

Official tags see: https://osu.ppy.sh/wiki/Beatmap/Beatmap_tags

.env.example

@@ -71,6 +71,7 @@ ENABLE_SUPPORTER_FOR_ALL_USERS=false
 ENABLE_ALL_BEATMAP_LEADERBOARD=false
 ENABLE_ALL_BEATMAP_PP=false
 SEASONAL_BACKGROUNDS='[]'
+BEATMAP_TAG_TOP_COUNT=2
 
 # Beatmap Cache Settings
 ENABLE_BEATMAP_PRELOAD=true