Stack trace order is inconsistent

**Is your feature request related to a problem? Please describe.**
Python stack traces place the most recent call last, Julia's place the most recent call first. When I the call stack has a bunch of Python function then a bunch of Julia functions, the most recent call is in the middle. I don't like that.

**Describe the solution you'd like**
It'd be nice if PythonCall printed Python stack traces in julian order and JuliaCall printed julia stack traces in pythonic order.

Julia's Base could also flip the order all stacktraces are printed in :P

The request concerns stack-trace formatting in PythonCall.jl and the referenced JuliaCall behavior, with Julia Base also mentioned as a possible broader scope. Start by locating the relevant formatting entry points and comparing mixed Python/Julia call stacks. Done means the ordering is consistent as requested, including clear behavior for mixed-language traces.

Written by the indexing model from the issue text.