Allow for dependencies to fallback to a JAR url provided in a url user param

[Gedochao]

Fixes #857

This allows for passing a dependency url through Scala CLI like this:

scala-cli run --dependency "tabby:tabby:0.2.3,url=https://github.com/bjornregnell/tabby/releases/download/v0.2.3/tabby_3-0.2.3.jar" UsingRemoteJar.scala

or even with a using directive:

//> using lib "tabby:tabby:0.2.3,url=https://github.com/bjornregnell/tabby/releases/download/v0.2.3/tabby_3-0.2.3.jar"
import tabby.Grid

object UsingRemoteJar extends App {
  println(Grid("a", "b", "c")(1, 2, 3))
}