Implement property for explicit jvmTarget for script definition...

Apply the property to the default JSR-223 script taking the value from
java.specification.version property, so effectively implementing
jvmTarget detection from current VM.
Also drop enforcing of target 1.8, using common default.
#KT-49329 fixed
#KT-40497 fixed

libraries/scripting/jsr223-test/testData/testJsr223Inlining.kt

@@ -0,0 +1,9 @@
+
+import javax.script.*
+
+inline fun<T> foo(body: () -> T): T = body()
+
+fun main() {
+    val scriptEngine = ScriptEngineManager().getEngineByExtension("kts")!!
+    scriptEngine.eval("println(foo { \"OK\" })")
+}