Extract cseabreeze into its own module

[ap--]

With Python=3.12 the Py limited API will have buffer support which should allow to build a cseabreeze module that is supported by all versions 3.12 and newer.

Once we extract cseabreeze we can make seabreeze noarch. We can at the same time force users to pick a backend on installation.

TODO

• [ ] extract cseabreeze when 3.12 is released
  • 3.12.0 candidate 1: Monday, 2023-07-31
  • 3.12.0 candidate 2: Monday, 2023-09-04
  • 3.12.0 final: Monday, 2023-10-02
• [ ] make seabreeze noarch
• [ ] force user to provide extra (runtime error if no extra is installed)

[ap--]

started extracting: www.github.com/ap--/seabreeze-c-backend