set up convention plugins

- tidy up build scripts to use convention plugins
- use centralised repo definition
- tidy up some of the build config

settings.gradle.kts

@@ -1,12 +1,25 @@
-/*
- * 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/7.6/userguide/multi_project_builds.html
- * This project uses @Incubating APIs which are subject to change.
- */
-
 rootProject.name = "urlencoder"
-include("lib")
+
+pluginManagement {
+  repositories {
+    mavenCentral()
+    gradlePluginPortal()
+  }
+}
+
+@Suppress("UnstableApiUsage")
+dependencyResolutionManagement {
+  repositoriesMode.set(RepositoriesMode.PREFER_SETTINGS)
+
+  repositories {
+    mavenCentral()
+    maven("https://oss.sonatype.org/content/repositories/snapshots") {
+      name = "Sonatype Snapshots"
+      mavenContent { snapshotsOnly() }
+    }
+  }
+}
+
+include(
+  ":lib",
+)