is duplicated by:

• SR-9362 swift package describe unnecessarily fetches dependencies

Issue Description:

$ swift package describe --type json

prints "Updating" messages to stdout, resulting in unparseable JSON.

e.g.

Updating https://github.com/foo-bar/foo.git
Updating https://github.com/foo-bar/bar.git
Updating https://github.com/foo-bar/baz.git
Updating https://github.com/foo-bar/quix.git
{
"name": "FooKit",
"path": "/Users/ankit/Source/FooKit/FooKit",

[JSON continues]

--

We should move all the other output on stderr and only keep JSON on stdout.