Override getText() in light classes to prevent decompiler errors on Kotlin sources

Fixes EA-58277
Fix resolution of Kotlin enums' values() and valueOf() from Java

Use the code from PsiClassImpl / ClsClassImpl, which for some reason is absent
in AbstractLightClass

 #KT-5591 Fixed
Fix resolve of Kotlin enum entries from Java

 #KT-5719 Fixed
Move KotlinLightMethod and KotlinLightElement to "jet.as.java.psi"
Eliminate package "light" from org.jetbrains.jet.asJava

Move everything to org.jetbrains.jet.asJava because classes for some light
elements were already there