Automatically create and configure build directory if it doesn't exist

I recently had to build a meson project and their way of configuring a project by just running meson build is very convenient. The idea is to support the same feature in CMake by making cmake build equivalent to cmake -B build -S . if build doesn't exist.

Currently cmake build errors with CMake Error: The source directory "/home/daan/projects/reproc/build" does not exist. Specify --help for usage, or press the help button on the CMake GUI.

I'm willing to implement this but there are valid arguments against adding this so I'm making an issue first.