[build] Restructure to composite build

conventions/src/main/kotlin/de.siphalor.tweed5.publishing.gradle.kts

@@ -0,0 +1,35 @@
+plugins {
+	`java-library`
+	`maven-publish`
+}
+
+group = rootProject.group
+version = rootProject.version
+
+publishing {
+	repositories {
+		if (project.hasProperty("siphalor.maven.user")) {
+			maven {
+				name = "Siphalor"
+				url = uri("https://maven.siphalor.de/upload.php")
+				credentials {
+					username = project.property("siphalor.maven.user") as String
+					password = project.property("siphalor.maven.password") as String
+				}
+			}
+		}
+	}
+
+	publications.all {
+		if (this is MavenPublication) {
+			pom {
+				name = project.property("module.name") as String
+				description = project.property("module.description") as String
+				url = project.property("git.url") as String
+				scm {
+					url = project.property("git.url") as String
+				}
+			}
+		}
+	}
+}