Wunused: Include import selector bounds in unused checks

[KacperFKorban]

closes lampepfl#17314

[szymon-rd]

Sadly it causes a new false positive in this snippet:

package foo:
  class Foo[T]
  given Foo[Int] = new Foo[Int]


package bar:
  import foo.{given foo.Foo[Int]}
  import foo.Foo

  val repro: Foo[Int] = summon[Foo[Int]]

-- Warning: Test.scala:7:14 ----------------------------------------------------
7 |  import foo.{given foo.Foo[Int]}
  |              ^^^^^^^^^^^^^^^^^^
  |              unused import
1 warning found