The JVM BE inlines calls to the underlying function in a $default stub
verbatim, e.g., without renaming LVT entries or regenerating anonymous
objects. This commit introduces the same behavior in the JVM IR BE.
Fixes KT-36769.
Specifically, this commit improves the stepping behavior of the IR
backend around functions with defaults.
- Improved line numbers in the default handler itself for better
stepping when inlined.
- Improved source information on default arguments
- Improved test coverage of stepping behavior in old and IR backends.
Improves the stepping behaviour around inline methods with default
arguments. In particular, we now accurately step through the
evaluation of default arguments, but do _not_ spuriously show the exit
from the $default handler.