Initial work on 1.13 forge resolver, fixes.

Moved java executable to its own util class.
Fixed artifact resolution links for older versions of forge.

1.13 support is going to be difficult because forge does not
make anything developer friendly.

src/index.ts

@@ -217,7 +217,8 @@ const testCommand: yargs.CommandModule = {
     handler: async (argv) => {
         console.debug(`Invoked test with mcVer ${argv.mcVer} forgeVer ${argv.forgeVer}`)
         console.log(process.cwd())
-        const resolver = ResolverRegistry.getForgeResolver('1.12.2', '14.23.5.2847', getRoot(), '', getBaseURL())
+        const resolver = ResolverRegistry.getForgeResolver(argv.mcVer as string,
+            argv.forgeVer as string, getRoot(), '', getBaseURL())
         if (resolver != null) {
             const mdl = await resolver.getModule()
             console.log(inspect(mdl, false, null, true))