- Switch from target:orderdeps() to target:get('deps') to show only
direct dependencies declared via add_deps(), not transitive ones
- Print output now shows all fields: root targets, name, kind, group,
default, and deps — matching the JSON structure
- Add kind assertion to test
Add a graph-oriented mode to `xmake show` for exporting target\ndependency relationships as JSON.\n\nThis adds `--target_graph` support for whole-project output and\noptional root-target filtering with `--target`.\n\nAdd a plugin test covering full-graph and single-target graph export.\n\nRefs #7475
