Revert "Identify data classes during extraction"

This reverts commit a61ba65, pending
adding a proper upgrade script for the DB change.

Author: smowton

java/kotlin-extractor/src/main/kotlin/KotlinFileExtractor.kt

@@ -397,10 +397,6 @@ open class KotlinFileExtractor(
                     } else if (kind != ClassKind.CLASS && kind != ClassKind.OBJECT) {
                         logger.warnElement("Unrecognised class kind $kind", c)
                     }
-
-                    if (c.isData) {
-                        tw.writeKtDataClasses(classId)
-                    }
                 }
 
                 val locId = tw.getLocation(c)

java/ql/lib/config/semmlecode.dbscheme

@@ -1232,7 +1232,3 @@ ktFunctionOriginalNames(
   unique int id: @method ref,
   string name: string ref
 )
-
-ktDataClasses(
-  unique int id: @class ref
-)

java/ql/lib/semmle/code/java/Type.qll

@@ -714,13 +714,6 @@ class CompanionObject extends Class {
   Field getInstance() { type_companion_object(_, result, this) }
 }
 
-/**
- * A Kotlin data class declaration.
- */
-class DataClass extends Class {
-  DataClass() { ktDataClasses(this) }
-}
-
 /**
  * A record declaration.
  */