Problem: Docs about how to obtain backtraces on Linux is not very
beginner-friendly; some users used to have difficulties in getting
stacktrace against Nvim crash.
For instance, the `core` dump file might not appear in the current
directory on Ubuntu systems with apport, and the current docs do not
fully cover such cases.
Solution: Add more hints about where core dump files can be found. For
example, on Ubuntu where apport is managing core dump files, users would
want to find them in `/var/lib/apport/coredump`.
Specifically, functions that are run in the context of the test runner
are put in module `test/testutil.lua` while the functions that are run
in the context of the test session are put in
`test/functional/testnvim.lua`.
Closes https://github.com/neovim/neovim/issues/27004.
Problem: Wiki contents are not discoverable and hard to maintain.
Solution: Move FAQ to runtime docs.
Co-authored-by: Christian Clason <c.clason@uni-graz.at>
