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.

libraries/tools/kotlin-gradle-plugin/src/main/kotlin/org/jetbrains/kotlin/gradle/internal/kapt/Kapt3KotlinGradleSubplugin.kt

@@ -366,6 +366,7 @@ class Kapt3KotlinGradleSubplugin : KotlinGradleSubplugin<KotlinCompile> {
 
         pluginOptions += SubpluginOption("useLightAnalysis", "${kaptExtension.useLightAnalysis}")
         pluginOptions += SubpluginOption("correctErrorTypes", "${kaptExtension.correctErrorTypes}")
+        pluginOptions += SubpluginOption("dumpDefaultParameterValues", "${kaptExtension.dumpDefaultParameterValues}")
         pluginOptions += SubpluginOption("mapDiagnosticLocations", "${kaptExtension.mapDiagnosticLocations}")
         pluginOptions += SubpluginOption("strictMode", "${kaptExtension.strictMode}")
         pluginOptions += SubpluginOption("showProcessorTimings", "${kaptExtension.showProcessorTimings}")

libraries/tools/kotlin-gradle-plugin/src/main/kotlin/org/jetbrains/kotlin/gradle/plugin/KaptExtension.kt

@@ -29,6 +29,8 @@ open class KaptExtension {
 
     open var correctErrorTypes: Boolean = false
 
+    open var dumpDefaultParameterValues: Boolean = false
+
     open var mapDiagnosticLocations: Boolean = false
 
     open var strictMode: Boolean = false