Allow `nix-env --query` to output aliases

[dyegoaurelio]

Is your feature request related to a problem?

The nix-env -qa command is a pretty helpful tool to find out information about package sets.

However, sometimes it's relevant to resolve all aliases of a package, not just he one that gets sorted with higher precedence.

Since, this is how nixos-search resolves it's packages,

https://github.com/NixOS/nixos-search/blob/d99e8c26f72f8b7b43148c92846bb2d463db3ff5/flake-info/src/commands/nixpkgs_info.rs#L12-L22

This would fix NixOS/nixos-search#975

Proposed solution

The dedupe logic happens here. We just need a cli option to tweak this behavior.

nix/src/libexpr/get-drvs.cc

Lines 335 to 338 in 7448aed

	/* Remove spurious duplicates (e.g., a set like `rec { x =
	derivation {...}; y = x;}'. */
	if (!done.insert(v.attrs()).second)
	return false;

Additional context

Checklist

• checked latest Nix manual (source)
• checked open feature issues and pull requests for possible duplicates

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