Add a `importlinter` block to `pyproject.toml`

[h8d13]

This is something I've seen @svartkanin comment on many PRs. So i thought we could perhaps try to fix/enforce it !

Example config:

[tool.importlinter]
root_package = "archinstall"
include_external_packages = false
exclude_type_checking_imports = true

[[tool.importlinter.contracts]]
name = "No circular imports between sibling subpackages"
type = "acyclic_siblings"
ancestors = ["archinstall", "archinstall.**"]

Currently flagged:

  - archinstall: default_profiles -> lib (16 imports), tui -> lib (4)
  - archinstall.lib: models -> disk, models -> locale, models -> profile, networking ->
    pacman
  - archinstall.lib.disk: partitioning_menu -> disk_menu

Maybe @correctmost can help with this to setup properly, perhaps integrate to PCH/CI.
Think this would help break cycles and keep it clean in the future.