[pkgman] Output dependency resolve as a tree

[NullAndVoid]

Using pkgman resolve-dependencies outputs a flattened list of all dependencies. This makes it impossible to utilize in order to figure out the dependency relationship that results in a particular package being resolved.

Add an option to output the dependency relationship as a tree, map or similar.

This came up when trying to figure out why Kate (a text editor) resolves a lot of dependencies that are not needed, such as audio- and video codecs.

​https://discuss.haiku-os.org/t/ported-applications-and-dependencies/14384

[waddlesplash]

PulkoMandy added a script to draw dependency graphs in hrev57477, which does something like what this is asking for, at least.