scalac -P option is not passed to scalac from the CLI

[earldouglas]

Version(s)
1.1.0

Describe the bug
When trying to use the continuations compiler via scala-cli, the required -P:continuations:enable argument is not being passed scalac when provided to scala-cli via the CLI.

To Reproduce

scala-cli \
  --scala 2.12.2 \
  --compiler-plugin org.scala-lang.plugins:::scala-continuations-plugin:1.0.3 \
  --dependency org.scala-lang.plugins::scala-continuations-library:1.0.3 \
  -P:continuations:enable \
  myscript.sc

Expected behaviour
The code should compile and run, but compilation fails with this code must be compiled with the Scala continuations plugin enabled. Running scala-cli with -v -v shows that the -P argument is not being passed to scalac.

Workaround
Setting the -P argument as a directive works correctly:

//> using option -P:continuations:enable

[SethTisue]

Note that --server=false doesn't improve the situation (I had hoped from #2621 it might)

[earldouglas]

Trying to force the argument with --scalac-option -P:continuations:enable also does not work.