[ci skip] Add a test plugin (#6133)

patches/server/0001-Setup-Gradle-project.patch

@@ -20,10 +20,10 @@ index 67fb370cad6924895a6b27052dbd5c1767e3f0c9..3e05459f27c4c5697ae65da504d67a6a
  /.project
 diff --git a/build.gradle.kts b/build.gradle.kts
 new file mode 100644
-index 0000000000000000000000000000000000000000..be565d252e326991f491cab3bfd3acc8356bbc7f
+index 0000000000000000000000000000000000000000..e76b9f9012c7ba7253f455fa92b3891737f4ffd3
 --- /dev/null
 +++ b/build.gradle.kts
-@@ -0,0 +1,138 @@
+@@ -0,0 +1,145 @@
 +import com.github.jengelman.gradle.plugins.shadow.transformers.Log4j2PluginsCacheFileTransformer
 +import com.github.jengelman.gradle.plugins.shadow.transformers.Transformer
 +import io.papermc.paperweight.util.Git
@@ -127,6 +127,13 @@ index 0000000000000000000000000000000000000000..be565d252e326991f491cab3bfd3acc8
 +    workingDir = rootProject.layout.projectDirectory.dir(
 +        providers.gradleProperty("runWorkDir").forUseAtConfigurationTime().orElse("run")
 +    ).get().asFile
++
++    if (rootProject.childProjects["test-plugin"] != null) {
++        val testPluginJar = rootProject.project(":test-plugin").tasks.jar.flatMap { it.archiveFile }
++        inputs.file(testPluginJar)
++        args("-add-plugin=${testPluginJar.get().asFile.absolutePath}")
++    }
++
 +    args("--nogui")
 +    systemProperty("net.kyori.adventure.text.warnWhenLegacyFormattingDetected", true)
 +    if (project.hasProperty("disableWatchdog")) {