Fix default host configuration property - make it not shared:

Shared instance is incorrect here and causes clashes when many
definitions are loaded in the same process.
Also make the diagnostics in case of clashes more verbose.

libraries/scripting/jvm/src/kotlin/script/experimental/jvm/jvmScriptingHostConfiguration.kt

@@ -25,9 +25,10 @@ val JvmScriptingHostConfigurationKeys.javaHome by PropertiesCollection.key<File>
 val ScriptingHostConfigurationKeys.jvm
     get() = JvmScriptingHostConfigurationBuilder()
 
-val defaultJvmScriptingHostConfiguration = ScriptingHostConfiguration {
-    getScriptingClass(JvmGetScriptingClass())
-}
+val defaultJvmScriptingHostConfiguration
+    get() = ScriptingHostConfiguration {
+        getScriptingClass(JvmGetScriptingClass())
+    }
 
 class JvmGetScriptingClass : GetScriptingClass {
 
@@ -52,7 +53,9 @@ class JvmGetScriptingClass : GetScriptingClass {
         if (dependencies == null) {
             dependencies = newDeps
         } else {
-            if (newDeps != dependencies) throw IllegalArgumentException("scripting configuration dependencies changed")
+            if (newDeps != dependencies) throw IllegalArgumentException(
+                "scripting configuration dependencies changed:\nold: ${dependencies?.joinToString { (it as? JvmDependency)?.classpath.toString() }}\nnew: ${newDeps?.joinToString { (it as? JvmDependency)?.classpath.toString() }}"
+            )
         }
 
         if (!baseClassLoaderIsInitialized) {