[packaging] Explore compiling `libssh` statically

This would need to only concern wheels published to PyPI (manylinux et al.)
The downstreams should still retain the ability to link against the OS-provided libs.

Some research suggests that this is implementable though `extra_objects` and `-fPIC`:

* https://cython-users.narkive.com/ocKNbCAj/wrap-c-static-library
* https://groups.google.com/g/cython-users/c/gQQ1JUtckBE/m/hGb78MrNEGYJ
* https://github.com/cython/cython/blob/404d958/Cython/Distutils/extension.py#L21
* https://github.com/cython/cython/blob/404d958/Cython/Debugger/Tests/TestLibCython.py#L138
* https://github.com/cython/cython/blob/404d958/Cython/Build/Dependencies.py#L151
* https://stackoverflow.com/a/2106051
* https://setuptools.pypa.io/en/latest/deprecated/distutils/setupscript.html#other-options
* https://setuptools.pypa.io/en/latest/userguide/ext_modules.html#extension-api-reference