Add settings.gradle file with repository downloader

This is necessary for Gradle to be able to download specified versions of the JDK when necessary. Not sure why it wasn't there before.

server/settings.gradle

@@ -0,0 +1,21 @@
+/*
+ * This file was generated by the Gradle 'init' task.
+ *
+ * The settings file is used to specify which projects to include in your build.
+ *
+ * Detailed information about configuring a multi-project build in Gradle can be found
+ * in the user manual at https://docs.gradle.org/5.6/userguide/multi_project_builds.html
+ */
+// This allows us to use the jresolver plugin. If we have
+// this plugin in place, we can specify a particular JDK version
+// in `build.gradle` and Gradle will download it for us if it's
+// not already installed on the system. This will hopefully make
+// it easier for people to run the project on a broad range of
+// computers without having to worry about installing the right
+// JDK version.
+
+plugins {
+    id 'org.gradle.toolchains.foojay-resolver-convention' version '0.8.0'
+}
+
+rootProject.name = 'server'