Fix --offline mode for scala-cli as scala installation via coursier

[Gedochao]

Fixes #3021

[tgodzik]

Lgtm!

[Gedochao]

Kudos to @kasiaMarek for the initial idea for this hack, btw.

[bishabosha]

Can confirm this works very well (pwd returns the directory of the coursier installed scala 3.5.0-RC4)-

/Users/jamie/Workspace/scala-cli/out/cli/3.3.3/standaloneLauncher.dest/launcher \
  --prog-name scala \
  --cli-default-scala-version 3.5.0-RC4 \
  -r file://$(pwd)/maven2 \
  --power -e 'println(sys.props("java.class.path"))' --offline --server=false
The `--offline` option is experimental
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
/var/folders/s7/dl7h4p057cz0fw4xgrv9snmm0000gn/T/10085725059665397379/.scala-build/10085725059665397379_39f5220048-c1fd01f914/classes/main:/Users/jamie/Library/Caches/Coursier/arc/https/github.com/scala/scala3/releases/download/3.5.0-RC4/scala3-3.5.0-RC4-aarch64-apple-darwin.tar.gz/scala3-3.5.0-RC4-aarch64-apple-darwin/maven2/org/scala-lang/scala3-library_3/3.5.0-RC4/scala3-library_3-3.5.0-RC4.jar:/Users/jamie/Library/Caches/Coursier/arc/https/github.com/scala/scala3/releases/download/3.5.0-RC4/scala3-3.5.0-RC4-aarch64-apple-darwin.tar.gz/scala3-3.5.0-RC4-aarch64-apple-darwin/maven2/org/scala-lang/scala-library/2.13.14/scala-library-2.13.14.jar

this is under the same conditions - coursier cache only has POM for scala3-compiler_3:3.5.0-RC4

[kasiaMarek]

Kudos to @kasiaMarek for the initial idea for this hack, btw.

Oh, how nice and thoughtful, though I believe it was actually @tgodzik's idea.