add util for assigning klib.signatureVersion

Author: aSemy

modules/bcv-gradle-plugin/src/main/kotlin/targets/KLibValidationSpec.kt

@@ -36,6 +36,13 @@ interface KLibValidationSpec {
   @get:Optional
   val signatureVersion: Property<KLibSignatureVersion>
 
+  /**
+   * Sets the value of [signatureVersion].
+   * @see signatureVersion
+   */
+  fun signatureVersion(version: Int): Unit =
+    signatureVersion.set(KLibSignatureVersion.of(version))
+
   /**
    * Fail validation if some build targets are not supported by the host compiler.
    * By default, ABI dumped only for supported files will be validated. This option makes validation behavior