feat: add support for post-partitioning scripts

[imobachgs]

Problem

It is not possible to execute post-partitioning scripts. The typical use case is deploying configuration files before the packages are installed. This can be used, for instance, to modify the behavior of an RPM script.

Solution

• Add support for running post-partitioning scripts.
• Import the postpartitioning-scripts section from AutoYaST profiles.

Testing

• Added a new unit test
• Tested manually

[coveralls]

Pull Request Test Coverage Report for Build 13366828894

Details

• 8 of 21 (38.1%) changed or added relevant lines in 5 files are covered.
• 17 unchanged lines in 2 files lost coverage.
• Overall coverage decreased (-0.04%) to 70.773%

---

Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
rust/agama-lib/src/scripts/store.rs	0	4	0.0%
rust/agama-lib/src/scripts/model.rs	0	9	0.0%

Files with Coverage Reduction	New Missed Lines	%
service/lib/agama/storage/finisher.rb	2	98.54%
service/lib/agama/manager.rb	15	81.15%

Totals
Change from base Build 13338745119:	-0.04%
Covered Lines:	17711
Relevant Lines:	25025

---

💛 - Coveralls