Move version command update checking to the implementation

This makes it easier for downstream projects (forks) to replace the
version fetching system with their own. It is as simple as implementing
an interface and overriding the default implementation of
org.bukkit.UnsafeValues#getVersionFetcher()

It also makes it easier for us to organize things like the version
history feature.

Lastly I have updated the paper implementation to check against the site
API rather than against jenkins.

Spigot-API-Patches/Add-an-asterisk-to-legacy-API-plugins.patch

@@ -7,13 +7,13 @@ Not here to name and shame, only so server admins can be aware of which
 plugins have and haven't been updated.
 
 diff --git a/src/main/java/org/bukkit/UnsafeValues.java b/src/main/java/org/bukkit/UnsafeValues.java
-index 72c5501e..71da4a79 100644
+index c0ff133d..b173e2ec 100644
 --- a/src/main/java/org/bukkit/UnsafeValues.java
 +++ b/src/main/java/org/bukkit/UnsafeValues.java
 @@ -0,0 +0,0 @@ public interface UnsafeValues {
-      * @return name
-      */
-     String getTimingsServerName();
+     default com.destroystokyo.paper.util.VersionFetcher getVersionFetcher() {
+         return new com.destroystokyo.paper.util.VersionFetcher.DummyVersionFetcher();
+     }
 +
 +    static boolean isLegacyPlugin(org.bukkit.plugin.Plugin plugin) {
 +        return !"1.13".equals(plugin.getDescription().getAPIVersion()) && !"1.14".equals(plugin.getDescription().getAPIVersion());