Switch from Scala String + comma separated values syntax to whitespace delimited list

[bishabosha]

Is your feature request related to a problem? Please describe.
To improve the ability to copy-paste snippets, such as compiler options.

Describe the solution you'd like
implement changes in the directives parser so that

//> using options "-Xasync", "-Xfatal-warnings"

can be written as

//> using options -Xasync -Xfatal-warnings

Quotes can still be used for when a value needs to include whitespace, with the same escape characters for scala strings.

Here is a larger example:

//> using scala 3.2.2
//> using toolkit latest
//> using options -Xfatal-warnings -Yexplicit-nulls -Ysafe-init -source:future
//> using dep com.lihaoyi::cask:0.9.0
//> using some.key "I have spaces"

We do not anticipate issues in adapting scala/vscode-scala-syntax to support the new syntax. Additionally, values are still of string type.

Describe alternatives you've considered
no alternative considered.

Additional context
Since directives will not become scala syntax, there is no need to reuse the same rules as the scala parser.

Discussed at the Scala Tooling Summit March 2023

[sjrd]

Bringing some additional associated spec that we discussed:

• For any value that does not immediately start with a ":
  • They cannot contain any " until the next whitespace
  • All other characters, including backslash, are taking verbatim.
• For values that start with a ":
  • They follow Scala syntax for single-line single-quoted strings
  • Including backslash-based escapes

[bjornregnell]

This is a very nice simplification for newcomers!