Rewrite plugin, use filenames in lockfile

fixtures/projects/dependency/maven-bom/kotlin/build.gradle.kts

@@ -0,0 +1,16 @@
+plugins {
+    java
+}
+
+repositories {
+    maven {
+        url = uri(System.getProperty("org.nixos.gradle2nix.m2"))
+        println(uri(System.getProperty("org.nixos.gradle2nix.m2")))
+        isAllowInsecureProtocol = true
+    }
+}
+
+dependencies {
+    implementation(platform("io.micrometer:micrometer-bom:1.5.1"))
+    implementation("io.micrometer:micrometer-core")
+}