Kapt: Add DUMP_DEFAULT_PARAMETER_VALUES flag (KT-29355)

Put initializers on fields when corresponding primary constructor
  parameters have a default value specified. The new behavior
  is available under the new 'DUMP_DEFAULT_PARAMETER_VALUES' flag.

Note that this doesn't affect regular functions with default parameter
  values, as well as primary constructor parameters without a
  'val' or 'var' keyword.

plugins/kapt3/kapt3-base/src/org/jetbrains/kotlin/kapt3/base/KaptOptions.kt

@@ -109,6 +109,7 @@ enum class KaptFlag(val description: String) {
     INFO_AS_WARNINGS("Info as warnings"),
     USE_LIGHT_ANALYSIS("Use light analysis"),
     CORRECT_ERROR_TYPES("Correct error types"),
+    DUMP_DEFAULT_PARAMETER_VALUES("Dump default parameter values"),
     MAP_DIAGNOSTIC_LOCATIONS("Map diagnostic locations"),
     STRICT("Strict mode"),
     INCLUDE_COMPILE_CLASSPATH("Detect annotation processors in compile classpath"),