Compatibility with the Fortran package manager

[awvwgk]

Is your feature request related to a problem? Please describe.

Currently, we support CMake and meson as build system, which work nicely for our purpose, however even meson has a significant entry barrier for developers. Having a solution which allows to immediately kick-off with the development of xtb and run the resulting binary from without configuring a binary would significantly speed up the development.

Describe the solution you'd like

The Fortran package manager (fpm) provides a solution which could compile and run most of xtb. We need to investigate whether there are features used in meson and CMake which cannot be supported by fpm. The fpm build would be primarily a developer feature and make xtb easier accessible, the deployment of the release would still happen with meson.