AirSpec: Scala 3 + Scala.js support

[xerial]

AirSpec for Scala 3 JVM is already available, but Scala.js with Scala 3 support is missing. Because of this, modules like json, msgpack, rx, rx-html, etc., which already support Scala 3, are not yet published for Scala.js + Scala 3.

TODOs:

• Extract runtime surface support to JVM specific source folder
• CompileTimeSurfaceFactory should not depend on wvlet.airframe.surface.reflect, dotty.tools.dotc.core.Types, which do not exist in Scala.js

cc: @exoego