Add //> using jvm "…" directive

**Is your feature request related to a problem? Please describe.**
Users can ask for a custom JVM on the command line, like `scala-cli --jvm 11 foo.sc`. Yet there's no corresponding using directive.

**Describe the solution you'd like**
Directives such as these should be accepted by Scala CLI:
```scala
//> using jvm "11"
//> using jvm "graalvm-java17:22.2.0"
```
