Add dependencies manager

Used to generate list of packages dependencies
for different distributions, and should improve
dependencies management by having them in each project.
This tools should gather the reason why a dependency is present,
so one can remove it when unused.

Rename deps script to packages

Move installer/packages to scripts and write tests

Remove packages-list make target

scripts/packages_test.py

@@ -0,0 +1,32 @@
+from pathlib import Path
+
+from .packages import list_packages, load_packages
+
+package_ini = """
+[common]
+postgresql = buster
+# Some comment
+curl = buster, bionic
+
+[legacy]
+apache2 = bionic
+
+[=development]
+ffmpeg = buster, bionic
+"""
+
+result1 = {"curl", "postgresql"}
+result2 = {"apache2", "curl", "ffmpeg"}
+
+
+def test_load_packages():
+    assert load_packages(package_ini, "buster", False) == result1
+    assert load_packages(package_ini, "bionic", True) == result2
+
+
+def test_list_packages(tmp_path: Path):
+    package_file = tmp_path / "packages.ini"
+    package_file.write_text(package_ini)
+
+    assert list_packages([tmp_path, package_file], "buster", False) == result1
+    assert list_packages([tmp_path, package_file], "bionic", True) == result2