[scaladoc] Allow to additional scalacOptions in Markdown code snippets

[WojciechMazur]

Extracted from #24734
Adds support for sc-opts: attribute that can be set in Markdown code snippets, allowing to pass additioanl arguments to snippet compiler.
This would allow us in #24734 to correctlly document behaviour of snippets producing error codes that require additional compiler options to be activated.

Example: ensure that -Werror makes given code to actually fail which can be checked with sc:fail,

 ```scala sc:fail sc-opts:-Werror,-explain def exampleShouldError(input: Option[String]): Unit = input match case Some("foo") => ??? ```.