New numpy custom dependency

Support for dependency('numpy') was added, via supporting the numpy-config tool and pkg-config support, both of which are available since NumPy 2.0.0.

Config-tool support is useful because it will work out of the box when numpy is installed, while the pkg-config file is located inside python's site-packages, which makes it impossible to use in an out of the box manner without setting PKG_CONFIG_PATH.