Extract extra imports provision into an extension, implement one ...

for script in the plugin, drop direct dependency on scripts from
FileScopeFactory

idea/resources/META-INF/extensions/compiler.xml

@@ -40,6 +40,9 @@
         <extensionPoint qualifiedName="org.jetbrains.kotlin.scriptTemplatesProvider"
                         interface="org.jetbrains.kotlin.script.ScriptTemplatesProvider"
                         area="IDEA_PROJECT"/>
+        <extensionPoint qualifiedName="org.jetbrains.kotlin.extraImportsProviderExtension"
+                        interface="org.jetbrains.kotlin.resolve.extensions.ExtraImportsProviderExtension"
+                        area="IDEA_PROJECT"/>
         <extensionPoint qualifiedName="org.jetbrains.kotlin.facetConfigurationExtension"
                         interface="org.jetbrains.kotlin.idea.facet.KotlinFacetConfigurationExtension"/>
         <extensionPoint qualifiedName="org.jetbrains.kotlin.versionInfoProvider"

idea/resources/META-INF/plugin-kotlin-extensions.xml

@@ -30,5 +30,6 @@
     <idePlatformKindTooling implementation="org.jetbrains.kotlin.idea.core.platform.impl.CommonIdePlatformKindTooling"/>
 
     <syntheticResolveExtension implementation="org.jetbrains.kotlin.scripting.compiler.plugin.ScriptingResolveExtension"/>
+    <extraImportsProviderExtension implementation="org.jetbrains.kotlin.scripting.compiler.plugin.ScriptExtraImportsProviderExtension"/>
   </extensions>
 </idea-plugin>