test.dep directives aren't migrated from test scope files by fix

[Gedochao]

Version(s)
d8b3313 / 1.5.4-94-gd8b33133f-SNAPSHOT

Describe the bug
When migrating directives with fix sub-command built-in rules, //> using dep directives from test scope files get migrated to //> using test.dependency directives in project.scala. However, inconsistently with that, //> using test.dependency` directives from test scope files don't get migrated at all.

To Reproduce
given

//> main.scala
//> using test.dependency "com.lihaoyi::os-lib:0.9.3"

and

//> smth.test.scala
//> using test.dependency org.scalatest::scalatest::3.2.9
//> using dep com.lihaoyi::pprint:0.9.0

when running

scala-cli fix . --power
# Some utilized features are marked as experimental:
#  - `fix` sub-command
#  - `--enable-scalafix=false` option
# Please bear in mind that non-ideal user experience should be expected.
# If you encounter any bugs or have feedback to share, make sure to reach out to the maintenance team at https://github.com/VirtusLab/scala-cli
# Running built-in rules...
# Writing project.scala
# Removing directives from smth.test.scala
#   Keeping:
#     //> using test.dependency org.scalatest::scalatest::3.2.9
# Built-in rules completed.

the resulting project configuration looks like this:

// project.scala
// Test
//> using test.dependency "com.lihaoyi::os-lib:0.9.3" "com.lihaoyi::pprint:0.9.0"

with one of the directives in smth.test.scala being kept back:

//> using test.dependency org.scalatest::scalatest::3.2.9

Expected behaviour
All //> using test.dependency directives should get migrated in this case.