feature(storage): API for solved and unsolved configs

[joseivanlopez]

Extend D-Bus and HTTP APIs to get the solved storage config:

$ busctl --address unix:path=/run/agama/bus call org.opensuse.Agama.Storage1 /org/opensuse/Agama/Storage1 org.opensuse.Agama.Storage1 GetSolvedConfig

$ curl -H @headers.txt http://localhost/api/storage/solved_config

[coveralls]

Pull Request Test Coverage Report for Build 11517714636

Details

• 67 of 77 (87.01%) changed or added relevant lines in 11 files are covered.
• 44 unchanged lines in 3 files lost coverage.
• Overall coverage decreased (-17.8%) to 71.473%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
rust/agama-lib/src/storage/client.rs	0	4	0.0%
rust/agama-server/src/storage/web.rs	0	6	0.0%
<!--	Total:	67	77	87.01%	-->

Files with Coverage Reduction	New Missed Lines	%
service/lib/agama/storage/proposal.rb	2	98.2%
service/lib/agama/config.rb	4	94.94%
service/lib/agama/dbus/storage/manager.rb	38	78.33%
<!--	Total:	44		-->

Totals
Change from base Build 11514248202:	-17.8%
Covered Lines:	16937
Relevant Lines:	23697

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💛 - Coveralls