Enable --debugger:native by default

[arnetheduck]

A simple way to improve the debugging DX is actually to just enable --debugger:native by default - this is useful on its own when running nim in gdb, and really shines when https://github.com/status-im/nim-libbacktrace is also enabled.

The default stacktrace/linetrace implementation as many limitations: it's slow, covers only the nim parts and doesn't work with tooling (profilers like vtune/prof, native debuggers and so on) - this is where native debugging symbols come in.

A downside is that binaries will look bigger because they now also host debugging information - there are two options here:

• be fine with it - users that care for their disk space usage can switch it off, but it's rare that this is a problem in 2025.
• use split debugging info, ie put it in a separate file