SLING-8730 Remove all GSP names and references

Make language name configurable (allows using custom/legacy name)
diff --git a/src/main/java/org/apache/sling/scripting/groovy/internal/GStringScriptEngineFactory.java b/src/main/java/org/apache/sling/scripting/groovy/internal/GStringScriptEngineFactory.java
index fdacffc..8e9fb95 100644
--- a/src/main/java/org/apache/sling/scripting/groovy/internal/GStringScriptEngineFactory.java
+++ b/src/main/java/org/apache/sling/scripting/groovy/internal/GStringScriptEngineFactory.java
@@ -105,7 +105,7 @@
 
     @Override
     public String getLanguageName() {
-        return "Groovy GString";
+        return configuration.language_name();
     }
 
     @Override
diff --git a/src/main/java/org/apache/sling/scripting/groovy/internal/GStringScriptEngineFactoryConfiguration.java b/src/main/java/org/apache/sling/scripting/groovy/internal/GStringScriptEngineFactoryConfiguration.java
index 4098d1d..8688e76 100644
--- a/src/main/java/org/apache/sling/scripting/groovy/internal/GStringScriptEngineFactoryConfiguration.java
+++ b/src/main/java/org/apache/sling/scripting/groovy/internal/GStringScriptEngineFactoryConfiguration.java
@@ -54,4 +54,10 @@
         "gstring"
     };
 
+    @AttributeDefinition(
+        name = "language name",
+        description = "The name of the script engine language."
+    )
+    String language_name() default "Groovy GString";
+
 }