Convenience scripts for system extensions

[fwilhe]

It might make sense to package utils for debugging in system extensions.

It would also be nice if they could be enabled in a convenient way that abstracts the need to download and copy them into a suitable location.

For example a script enable-debug could download and enable a system extension containing tools like gdb and strace. This could work regardless if we're using the debian or the Garden Linux apt sources as the tools that are packaged in the system extensions don't need to be in the Garden Linux repos.