Don't call .getFqName() when writing package src class name

Package$src class names contain dollars, and JvmClassName.getFqName() doesn't
work very well for such names
Delete JvmClassName.byType

Replace JvmClassName by ASM Type in many places of JVM codegen: it wasn't used
to abstract anything, but there was a lot of useless conversions between the
two
Refactor CodegenBinding.getJvmInternalFQNameImpl

Simplify code, make sure empty string is never returned
Delete unneeded method from PsiCodegenPredictor
Delete unused slice in CodegenBinding
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