refactor(vm): separate argument parsing and device creation

[Lencerf]

Introduce a unified VM config structure, let CLI focuse on argument
parsing only, and move device creation into core crate.

[coveralls]

Pull Request Test Coverage Report for Build 20530326650

Details

• 96 of 179 (53.63%) changed or added relevant lines in 4 files are covered.
• 1 unchanged line in 1 file lost coverage.
• Overall coverage increased (+0.2%) to 26.438%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
alioth/src/virtio/dev/net/tap.rs	0	1	0.0%
alioth/src/hv/hv.rs	0	3	0.0%
alioth-cli/src/boot.rs	96	110	87.27%
alioth/src/vm/vm.rs	0	65	0.0%

Files with Coverage Reduction	New Missed Lines	%
alioth-cli/src/boot.rs	1	84.0%

Totals
Change from base Build 20509167161:	0.2%
Covered Lines:	3583
Relevant Lines:	14014

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💛 - Coveralls